Cousin primes: Difference between revisions
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:* the MathWorld entry: [https://mathworld.wolfram.com/CousinPrimes.html cousin primes].
<br><br>
=={{header|11l}}==
{{trans|Nim}}
<syntaxhighlight lang="11l">V LIMIT = 1000
F isPrime(n)
I (n [&] 1) == 0
R n == 2
V m = 3
L m * m <= n
I n % m == 0
R 0B
m += 2
R 1B
V PrimeList = (2 .< LIMIT).filter(n -> isPrime(n))
V PrimeSet = Set(PrimeList)
V cousinList = PrimeList.filter(n -> (n + 4) C PrimeSet).map(n -> (n, n + 4))
print(‘Found #. cousin primes less than #.:’.format(cousinList.len, LIMIT))
L(cousins) cousinList
print(String(cousins).center(10), end' I (L.index + 1) % 7 == 0 {"\n"} E ‘ ’)
print()</syntaxhighlight>
{{out}}
<pre>
Found 41 cousin primes less than 1000:
(3, 7) (7, 11) (13, 17) (19, 23) (37, 41) (43, 47) (67, 71)
(79, 83) (97, 101) (103, 107) (109, 113) (127, 131) (163, 167) (193, 197)
(223, 227) (229, 233) (277, 281) (307, 311) (313, 317) (349, 353) (379, 383)
(397, 401) (439, 443) (457, 461) (463, 467) (487, 491) (499, 503) (613, 617)
(643, 647) (673, 677) (739, 743) (757, 761) (769, 773) (823, 827) (853, 857)
(859, 863) (877, 881) (883, 887) (907, 911) (937, 941) (967, 971)
</pre>
=={{header|Action!}}==
{{libheader|Action! Sieve of Eratosthenes}}
<syntaxhighlight lang="action!">INCLUDE "H6:SIEVE.ACT"
PROC Main()
DEFINE MAX="999"
BYTE ARRAY primes(MAX+1)
INT i,count=[0]
Put(125) PutE() ;clear the screen
Sieve(primes,MAX+1)
FOR i=2 TO MAX-4
DO
IF primes(i)=1 AND primes(i+4)=1 THEN
PrintF("(%I,%I) ",i,i+4)
count==+1
FI
OD
PrintF("%E%EThere are %I pairs",count)
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Cousin_primes.png Screenshot from Atari 8-bit computer]
<pre>
(3,7) (7,11) (13,17) (19,23) (37,41) (43,47) (67,71) (79,83) (97,101) (103,107)
(109,113) (127,131) (163,167) (193,197) (223,227) (229,233) (277,281) (307,311)
(313,317) (349,353) (379,383) (397,401) (439,443) (457,461) (463,467) (487,491)
(499,503) (613,617) (643,647) (673,677) (739,743) (757,761) (769,773) (823,827)
(853,857) (859,863) (877,881) (883,887) (907,911) (937,941) (967,971)
There are 41 pairs
</pre>
=={{header|Ada}}==
<
procedure Cousin_Primes is
Line 65 ⟶ 134:
New_Line;
Put_Line (Count'Image & " pairs.");
end Cousin_Primes;</
{{out}}
<pre>[ 3, 7] [ 7, 11] [ 13, 17] [ 19, 23] [ 37, 41] [ 43, 47] [ 67, 71] [ 79, 83]
Line 76 ⟶ 145:
=={{header|ALGOL 68}}==
{{libheader|ALGOL 68-primes}}
<syntaxhighlight lang="algol68">BEGIN # find cousin primes - pairs of primes that differ by 4 #
# sieve the primes
PR read "primes.incl.a68" PR
# returns text right padded to length, if it is shorter #
PROC right pad = ( STRING text, INT length )STRING:
Line 97 ⟶ 159:
# look through the primes for cousins #
INT p count := 0;
FOR i TO
IF prime[ i ] THEN
IF prime[ i + 4 ] THEN
# have a pair of cousin primes #
p count +:= 1;
FI
FI
OD;
print( ( newline, "Found ", whole( p count, 0 ), " cousin primes", newline ) )
END</
{{out}}
<pre>
109-113 127-131 163-167 193-197 223-227 229-233 277-281 307-311 313-317 349-353
379-383 397-401 439-443 457-461 463-467 487-491 499-503 613-617 643-647 673-677
739-743 757-761 769-773 823-827 853-857 859-863 877-881 883-887 907-911 937-941
967-971
Found 41 cousin primes
</pre>
=={{header|ALGOL W}}==
<
integer MAX_PRIME;
MAX_PRIME := 1000;
Line 166 ⟶ 209:
write( i_w := 1, s_w := 0, "Found ", cCount, " cousin prime pairs up to ", MAX_PRIME )
end
end.</
{{out}}
<pre>
Line 178 ⟶ 221:
=={{header|APL}}==
<
{{out}}
Line 226 ⟶ 269:
=={{header|AppleScript}}==
<
script o
property numberList : {missing value}
Line 251 ⟶ 294:
if (p - 4 is in primes) then set end of output to {p - 4, p's contents}
end repeat
return {|cousin prime pairs < 1000|:output, |count thereof|:(count output)}</
{{output}}
<
=={{header|Arturo}}==
<
primesUpto: select 0..upto => prime?
return select primesUpto => [prime? & + 4]
]
print map cousins 1000 'c -> @[c, c + 4]</
{{out}}
Line 270 ⟶ 313:
=={{header|AWK}}==
<syntaxhighlight lang="awk">
# syntax: GAWK -f COUSIN_PRIMES.AWK
BEGIN {
Line 294 ⟶ 337:
return(1)
}
</syntaxhighlight>
{{out}}
<pre>
Line 306 ⟶ 349:
=={{header|BASIC}}==
<
20 FOR P=2 TO SQR(L)
30 IF S(P) THEN 50
Line 315 ⟶ 358:
80 IF S(P)+S(P+4)=0 THEN N=N+1: PRINT P,P+4
90 NEXT
100 PRINT "There are";N;"cousin prime pairs below";L</
{{out}}
Line 363 ⟶ 406:
=={{header|BCPL}}==
<
manifest $( LIMIT = 1000 $)
Line 394 ⟶ 437:
$)
writef("*N%N pairs found.*N", count)
$)</
{{out}}
<pre style="height:14em;">3, 7
Line 441 ⟶ 484:
=={{header|C}}==
<
#include <string.h>
Line 469 ⟶ 512:
printf("There are %d cousin prime pairs below %d.\n", count, LIMIT);
return 0;
}</
{{out}}
Line 517 ⟶ 560:
=={{header|COBOL}}==
<
PROGRAM-ID. COUSIN-PRIMES.
Line 567 ⟶ 610:
FLAG-PRIME. MOVE 1 TO PRIME-FLAG(Q).
UNFLAG-PRIME. MOVE 0 TO PRIME-FLAG(Q).
DONE. EXIT.</
{{out}}
<pre style='height:14em;'> 3 7
Line 613 ⟶ 656:
=={{header|Cowgol}}==
<
const LIMIT := 1000;
Line 650 ⟶ 693:
print(" cousin prime pairs below ");
print_i16(LIMIT);
print_nl();</
{{out}}
Line 699 ⟶ 742:
=={{header|F_Sharp|F#}}==
This task uses [http://www.rosettacode.org/wiki/Extensible_prime_generator#The_functions Extensible Prime Generator (F#)]
<
// Cousin Primes: Nigel Galloway. April 2nd., 2021
primes32()|>Seq.pairwise|>Seq.takeWhile(fun(_,n)->n<1000)|>Seq.filter(fun(n,g)->g-n=4)|>Seq.iter(fun(n,g)->printf "(%d,%d) "n g); printfn ""
</syntaxhighlight>
{{out}}
<pre>
Line 709 ⟶ 752:
=={{header|Factor}}==
{{works with|Factor|0.99 2021-02-05}}
<
sequences ;
Line 716 ⟶ 759:
[ [ prime? ] all? ] lfilter ;
lcousins [ last 1000 < ] lwhile [ . ] leach</
{{out}}
<pre style="height:14em">
Line 765 ⟶ 808:
=={{header|FOCAL}}==
<
01.20 T %4
01.30 F N=3,2,996;D 2
Line 783 ⟶ 826:
03.50 S K=K+1
03.60 G 3.2
03.70 S A=0</
{{out}}
Line 829 ⟶ 872:
= 967= 971
AMOUNT OF COUSIN PRIME PAIRS= 41</pre>
=={{header|Forth}}==
{{works with|Gforth}}
<syntaxhighlight lang="forth">: prime? ( n -- ? ) here + c@ 0= ;
: not-prime! ( n -- ) here + 1 swap c! ;
: prime-sieve ( n -- )
here over erase
0 not-prime!
1 not-prime!
2
begin
2dup dup * >
while
dup prime? if
2dup dup * do
i not-prime!
dup +loop
then
1+
repeat
2drop ;
: cousin-primes ( n -- )
dup prime-sieve
0
over 4 - 0 do
i prime? if i 4 + prime? if
1+
." (" i 3 .r ." , " i 4 + 3 .r ." )"
dup 5 mod 0= if cr else space then
then then
loop
swap
cr ." Number of cousin prime pairs < " . ." is " . cr ;
1000 cousin-primes
bye</syntaxhighlight>
{{out}}
<pre>
( 3, 7) ( 7, 11) ( 13, 17) ( 19, 23) ( 37, 41)
( 43, 47) ( 67, 71) ( 79, 83) ( 97, 101) (103, 107)
(109, 113) (127, 131) (163, 167) (193, 197) (223, 227)
(229, 233) (277, 281) (307, 311) (313, 317) (349, 353)
(379, 383) (397, 401) (439, 443) (457, 461) (463, 467)
(487, 491) (499, 503) (613, 617) (643, 647) (673, 677)
(739, 743) (757, 761) (769, 773) (823, 827) (853, 857)
(859, 863) (877, 881) (883, 887) (907, 911) (937, 941)
(967, 971)
Number of cousin prime pairs < 1000 is 41
</pre>
=={{header|FreeBASIC}}==
Use one of the primality testing examples as an include.
<
dim as uinteger c=0, i
Line 841 ⟶ 936:
print using "Pair ##: #### and ####"; c; i; i+4
end if
next i</
{{out}}
Line 890 ⟶ 985:
=={{header|Go}}==
{{trans|Wren}}
<
import "fmt"
Line 936 ⟶ 1,031:
}
fmt.Printf("\n\n%d pairs found\n", count)
}</
{{out}}
Line 952 ⟶ 1,047:
=={{header|Haskell}}==
<
import Data.List.Split (chunksOf)
import Data.Numbers.Primes (isPrime, primes)
Line 983 ⟶ 1,078:
let ws = maximum . fmap length <$> transpose rows
pw = printf . flip intercalate ["%", "s"] . show
in unlines $ intercalate gap . zipWith pw ws <$> rows</
{{Out}}
<pre>41 cousin prime pairs:
Line 998 ⟶ 1,093:
=={{header|J}}==
<
{{out}}
<pre style="height:14em;"> 3 7
Line 1,042 ⟶ 1,137:
967 971
Amount: 41</pre>
(In this example, we can get away with finding primes where adding 4 gives us another prime. But if the task had asked for cousin prime pairs less than 100, we would want to avoid the pair 97,101. And the simplest way of addressing that issue would have been to find primes where subtracting 4 gives us another prime.)
=={{header|jq}}==
{{works with|jq}}
'''Works with gojq, the Go implementation of jq'''
For the definition of `is_prime` used here, see https://rosettacode.org/wiki/Additive_primes<syntaxhighlight lang="jq"># Output: a stream
def cousins:
# [2,6] is not a cousin so we can start at 3
range(3;.;2)
| select(is_prime and (.+4 | is_prime))
| [., .+4];
997 | cousins</syntaxhighlight>
{{out}}
See below.
'''The Count'''
To compute the pairs and the count at the same time without saving them as an array:<syntaxhighlight lang="jq"># Use null as the EOS marker
foreach ((997|cousins),null) as $c (-1; .+1; if $c == null then "\nCount is \(.)" else $c end)</syntaxhighlight>
{{out}}
<pre>
[3,7]
[7,11]
[13,17]
[19,23]
[37,41]
[43,47]
[67,71]
[79,83]
[97,101]
[103,107]
[109,113]
[127,131]
[163,167]
[193,197]
[223,227]
[229,233]
[277,281]
[307,311]
[313,317]
[349,353]
[379,383]
[397,401]
[439,443]
[457,461]
[463,467]
[487,491]
[499,503]
[613,617]
[643,647]
[673,677]
[739,743]
[757,761]
[769,773]
[823,827]
[853,857]
[859,863]
[877,881]
[883,887]
[907,911]
[937,941]
[967,971]
Count is 41
</pre>
=={{header|Julia}}==
{{trans|Wren}}
<
let
Line 1,059 ⟶ 1,222:
println("\n\n$pcount pairs found.")
end
</
<pre>
Cousin prime pairs under 1,000:
Line 1,070 ⟶ 1,233:
41 pairs found.
</pre>
=={{header|Lua}}==
<syntaxhighlight lang="lua">
do -- find primes p where p+4 is also prime
local MAX_PRIME = 1000
local p = {} -- sieve the odd primes to MAX_PRIME
for i = 3, MAX_PRIME, 2 do p[ i ] = true end
for i = 3, math.floor( math.sqrt( MAX_PRIME ) ), 2 do
if p[ i ] then
for s = i * i, MAX_PRIME, i + i do p[ s ] = false end
end
end
local function fmt ( n ) return string.format( "%3d", n ) end
io.write( "Cousin primes under ", MAX_PRIME, ":\n" )
local cCount = 0
for i = 3, MAX_PRIME - 4, 2 do
if p[ i ] and p[ i + 4 ] then
cCount = cCount + 1
io.write( "[ ", fmt( i ), " ", fmt( i + 4 ), " ]"
, ( cCount % 8 == 0 and "\n" or " " )
)
end
end
io.write( "\nFound ", cCount, " cousin primes\n" )
end
</syntaxhighlight>
{{out}}
<pre>
Cousin primes under 1000:
[ 3 7 ] [ 7 11 ] [ 13 17 ] [ 19 23 ] [ 37 41 ] [ 43 47 ] [ 67 71 ] [ 79 83 ]
[ 97 101 ] [ 103 107 ] [ 109 113 ] [ 127 131 ] [ 163 167 ] [ 193 197 ] [ 223 227 ] [ 229 233 ]
[ 277 281 ] [ 307 311 ] [ 313 317 ] [ 349 353 ] [ 379 383 ] [ 397 401 ] [ 439 443 ] [ 457 461 ]
[ 463 467 ] [ 487 491 ] [ 499 503 ] [ 613 617 ] [ 643 647 ] [ 673 677 ] [ 739 743 ] [ 757 761 ]
[ 769 773 ] [ 823 827 ] [ 853 857 ] [ 859 863 ] [ 877 881 ] [ 883 887 ] [ 907 911 ] [ 937 941 ]
[ 967 971 ]
Found 41 cousin primes
</pre>
=={{header|MAD}}==
<
BOOLEAN PRIME
DIMENSION PRIME(1000)
Line 1,099 ⟶ 1,299:
VECTOR VALUES COUSIN = $I4,2H: ,I4*$
VECTOR VALUES TOTAL = $15HTOTAL COUSINS: ,I2*$
END OF PROGRAM </
{{out}}
Line 1,145 ⟶ 1,345:
967: 971
TOTAL COUSINS: 41</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">primes = Prime@Range[PrimePi[1000] - 1];
primes = {primes, primes + 4} // Transpose;
Select[primes, AllTrue[PrimeQ]]
Length[%]</syntaxhighlight>
{{out}}
<pre>{{3,7},{7,11},{13,17},{19,23},{37,41},{43,47},{67,71},{79,83},{97,101},{103,107},{109,113},{127,131},{163,167},{193,197},{223,227},{229,233},{277,281},{307,311},{313,317},{349,353},{379,383},{397,401},{439,443},{457,461},{463,467},{487,491},{499,503},{613,617},{643,647},{673,677},{739,743},{757,761},{769,773},{823,827},{853,857},{859,863},{877,881},{883,887},{907,911},{937,941},{967,971}}
41</pre>
=={{header|Nim}}==
We use a simple primality test (which is in fact executed at compile time). For large values of N, it would be better to use a sieve of Erathostenes and to replace the constants “PrimeList” and “PrimeSet” by read-only variables.
<
const N = 1000
Line 1,174 ⟶ 1,383:
stdout.write ($cousins).center(10)
stdout.write if (i+1) mod 7 == 0: '\n' else: ' '
echo()</
{{out}}
Line 1,188 ⟶ 1,397:
{{works with|Free Pascal}}
{{works with|Delphi}}Sieving only odd numbers.
<
//Free Pascal Compiler version 3.2.1 [2020/11/03] for x86_64fpc
{$IFDEF FPC}
Line 1,298 ⟶ 1,507:
setlength(primes,0);
END.</
{{out}}
<pre>
Line 1,321 ⟶ 1,530:
=={{header|Perl}}==
{{libheader|ntheory}}
<
use feature 'say';
use ntheory 'is_prime';
Line 1,327 ⟶ 1,536:
my($limit, @cp) = 1000;
is_prime($_) and is_prime($_+4) and push @cp, "$_/@{[$_+4]}" for 2..$limit;
say @cp . " cousin prime pairs < $limit:\n" . (sprintf "@{['%8s' x @cp]}", @cp) =~ s/(.{56})/$1\n/gr;</
{{out}}
<pre>41 cousin prime pairs < 1000:
Line 1,338 ⟶ 1,547:
=={{header|Phix}}==
<!--<
<span style="color: #008080;">function</span> <span style="color: #000000;">has_cousin</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">p</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #7060A8;">is_prime</span><span style="color: #0000FF;">(</span><span style="color: #000000;">p</span><span style="color: #0000FF;">+</span><span style="color: #000000;">4</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">=</span><span style="color: #000000;">2</span> <span style="color: #008080;">to</span> <span style="color: #000000;">7</span> <span style="color: #008080;">do</span>
Line 1,346 ⟶ 1,555:
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%,d cousin prime pairs less than %,d found: %v\n"</span><span style="color: #0000FF;">,{</span><span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">),</span><span style="color: #000000;">tn</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">shorten</span><span style="color: #0000FF;">(</span><span style="color: #000000;">res</span><span style="color: #0000FF;">,</span><span style="color: #008000;">""</span><span style="color: #0000FF;">,</span><span style="color: #7060A8;">min</span><span style="color: #0000FF;">(</span><span style="color: #000000;">4</span><span style="color: #0000FF;">,</span><span style="color: #000000;">5</span><span style="color: #0000FF;">-</span><span style="color: #7060A8;">floor</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">/</span><span style="color: #000000;">2</span><span style="color: #0000FF;">)))})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--</
<small>(Uses tn-9 instead of the more obvious tn-4 since none of 96,95,94,93,92 or similar with 9..99999 prefix could ever be prime. Note that {97,101} is deliberately excluded from < 100.)</small>
{{out}}
Line 1,359 ⟶ 1,568:
=={{header|Python}}==
<
from itertools import chain, takewhile
Line 1,484 ⟶ 1,693:
# MAIN ---
if __name__ == '__main__':
main()</
{{Out}}
<pre>41 cousin pairs below 1000:
Line 1,499 ⟶ 1,708:
(877, 881) (883, 887) (907, 911) (937, 941)
(967, 971)</pre>
=={{header|Quackery}}==
<code>eratosthenes</code> and <code>isprime</code> are defined at [[Sieve of Eratosthenes#Quackery]].
<syntaxhighlight lang="Quackery"> 1000 eratosthenes
[] 1000 4 - times
[ i^ isprime
i^ 4 + isprime
and if
[ i^ dup 4 + join
nested join ] ]
dup echo cr cr
size echo
</syntaxhighlight>
{{out}}
<pre>[ [ 3 7 ] [ 7 11 ] [ 13 17 ] [ 19 23 ] [ 37 41 ] [ 43 47 ] [ 67 71 ] [ 79 83 ] [ 97 101 ] [ 103 107 ] [ 109 113 ] [ 127 131 ] [ 163 167 ] [ 193 197 ] [ 223 227 ] [ 229 233 ] [ 277 281 ] [ 307 311 ] [ 313 317 ] [ 349 353 ] [ 379 383 ] [ 397 401 ] [ 439 443 ] [ 457 461 ] [ 463 467 ] [ 487 491 ] [ 499 503 ] [ 613 617 ] [ 643 647 ] [ 673 677 ] [ 739 743 ] [ 757 761 ] [ 769 773 ] [ 823 827 ] [ 853 857 ] [ 859 863 ] [ 877 881 ] [ 883 887 ] [ 907 911 ] [ 937 941 ] [ 967 971 ] ]
41
</pre>
=={{header|REXX}}==
This REXX version allows the limit to be specified, as well as the number of cousin prime pairs to be shown per line.
<
parse arg hi cols . /*get optional number of primes to find*/
if hi=='' | hi=="," then hi= 1000 /*Not specified? Then assume default.*/
Line 1,538 ⟶ 1,770:
#= # + 1; @.#= j; !.j= 1 /*bump prime count; assign prime & flag*/
end /*j*/
return</
{{out|output|text= when using the default inputs:}}
<pre>
Line 1,554 ⟶ 1,786:
===Filter===
Favoring brevity over efficiency due to the small range of n, the most concise solution is:
<syntaxhighlight lang="raku"
{{out}}
<pre>
Line 1,562 ⟶ 1,794:
A more efficient and versatile approach is to generate an infinite list of cousin primes, using this info from https://oeis.org/A023200 :
:Apart from the first term, all terms are of the form 6n + 1.
<syntaxhighlight lang="raku"
my $count = @cousins.first: :k, *.[0] > 1000;
.say for @cousins.head($count).batch(9);</
{{out}}
<pre>
Line 1,576 ⟶ 1,808:
=={{header|Ring}}==
<
load "stdlib.ring"
Line 1,610 ⟶ 1,842:
see "done..." + nl
</syntaxhighlight>
{{out}}
<pre>
Line 1,627 ⟶ 1,859:
found 81 unique cousin primes.
done...
</pre>
=={{header|RPL}}==
{{works with|HP|49}}
≪ { } → cousins
≪ 2 3 5
'''DO'''
ROT DROP DUP NEXTPRIME
'''CASE'''
DUP 4 PICK - 4 == '''THEN''' PICK3 OVER R→C 'cousins' SWAP STO+ '''END'''
DUP2 - -4 == '''THEN''' DUP2 R→C 'cousins' SWAP STO+ '''END'''
'''END'''
'''UNTIL''' DUP 1000 ≥ '''END'''
3 DROPN
cousins DUP SIZE
≫ ≫ '<span style="color:blue">TASK</span>' STO
{{out}}
<pre>
2: { (3., 7.) (7., 11.) (13., 17.) (19., 23.) (37., 41.) (43., 47.) (67., 71.) (79., 83.) (97., 101.) (103., 107.) (109., 113.) (127., 131.) (163., 167.) (193., 197.) (223., 227.) (229., 233.) (277., 281.) (307., 311.) (313., 317.) (349., 353.) (379., 383.) (397., 401.) (439., 443.) (457., 461.) (463., 467.) (487., 491.) (499., 503.) (613., 617.) (643., 647.) (673., 677.) (739., 743.) (757., 761.) (769., 773.) (823., 827.) (853., 857.) (859., 863.) (877., 881.) (883., 887.) (907., 911.) (937., 941.) (967., 971.) }
1: 41
</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">require 'prime'
primes = Prime.each(1000).to_a
p cousins = primes.filter_map{|pr| [pr, pr+4] if primes.include?(pr+4) }
puts "#{cousins.size} cousins found."
</syntaxhighlight>
{{out}}
<pre>[[3, 7], [7, 11], [13, 17], [19, 23], [37, 41], [43, 47], [67, 71], [79, 83], [97, 101], [103, 107], [109, 113], [127, 131], [163, 167], [193, 197], [223, 227], [229, 233], [277, 281], [307, 311], [313, 317], [349, 353], [379, 383], [397, 401], [439, 443], [457, 461], [463, 467], [487, 491], [499, 503], [613, 617], [643, 647], [673, 677], [739, 743], [757, 761], [769, 773], [823, 827], [853, 857], [859, 863], [877, 881], [883, 887], [907, 911], [937, 941], [967, 971]]
41 cousins found.
</pre>
=={{header|Seed7}}==
<
const func boolean: isPrime (in integer: number) is func
Line 1,662 ⟶ 1,925:
end for;
writeln("\n" <& count <& " cousin prime pairs found < 1000.");
end func;</
{{out}}
<pre style="height:14em">
Line 1,711 ⟶ 1,974:
=={{header|Sidef}}==
<
var pairs = (limit-5).primes.map { [_, _+4] }.grep { .tail.is_prime }
say "Cousin prime pairs whose elements are less than #{limit.commify}:"
say pairs
say "\n#{pairs.len} pairs found"</
{{out}}
<pre>
Line 1,723 ⟶ 1,986:
41 pairs found
</pre>
=={{header|Swift}}==
<syntaxhighlight lang="swift">import Foundation
func primeSieve(limit: Int) -> [Bool] {
guard limit > 0 else {
return []
}
var sieve = Array(repeating: true, count: limit)
sieve[0] = false
if limit > 1 {
sieve[1] = false
}
if limit > 4 {
for i in stride(from: 4, to: limit, by: 2) {
sieve[i] = false
}
}
var p = 3
var sq = p * p
while sq < limit {
if sieve[p] {
for i in stride(from: sq, to: limit, by: p * 2) {
sieve[i] = false
}
}
sq += (p + 1) * 4;
p += 2
}
return sieve
}
func toString(_ number: Int) -> String {
return String(format: "%3d", number)
}
let limit = 1000
let sieve = primeSieve(limit: limit)
var count = 0
for p in 0..<limit - 4 {
if sieve[p] && sieve[p + 4] {
print("(\(toString(p)), \(toString(p + 4)))", terminator: "")
count += 1
print(count % 5 == 0 ? "\n" : " ", terminator: "")
}
}
print("\nNumber of cousin prime pairs < \(limit): \(count)")</syntaxhighlight>
{{out}}
<pre>
( 3, 7) ( 7, 11) ( 13, 17) ( 19, 23) ( 37, 41)
( 43, 47) ( 67, 71) ( 79, 83) ( 97, 101) (103, 107)
(109, 113) (127, 131) (163, 167) (193, 197) (223, 227)
(229, 233) (277, 281) (307, 311) (313, 317) (349, 353)
(379, 383) (397, 401) (439, 443) (457, 461) (463, 467)
(487, 491) (499, 503) (613, 617) (643, 647) (673, 677)
(739, 743) (757, 761) (769, 773) (823, 827) (853, 857)
(859, 863) (877, 881) (883, 887) (907, 911) (937, 941)
(967, 971)
Number of cousin prime pairs < 1000: 41
</pre>
Line 1,728 ⟶ 2,052:
{{libheader|Wren-math}}
{{libheader|Wren-fmt}}
<
import "./fmt" for Fmt
var c = Int.primeSieve(999, false)
Line 1,744 ⟶ 2,068:
i = i + 2
}
System.print("\n\n%(count) pairs found")</
{{out}}
Line 1,757 ⟶ 2,081:
41 pairs found
</pre>
=={{header|XPL0}}==
<syntaxhighlight lang "XPL0">include xpllib; \For IsPrime and Print
int N, C;
[C:= 0;
for N:= 2 to 1000-1-4 do
[if IsPrime(N) then
if IsPrime(N+4) then
[Print("(%3.0f, %3.0f) ", float(N), float(N+4));
C:= C+1;
if rem(C/6) = 0 then CrLf(0);
];
];
Print("\nThere are %d cousin primes less than 1000.\n", C);
]</syntaxhighlight>
{{out}}
<pre>
( 3, 7) ( 7, 11) ( 13, 17) ( 19, 23) ( 37, 41) ( 43, 47)
( 67, 71) ( 79, 83) ( 97, 101) (103, 107) (109, 113) (127, 131)
(163, 167) (193, 197) (223, 227) (229, 233) (277, 281) (307, 311)
(313, 317) (349, 353) (379, 383) (397, 401) (439, 443) (457, 461)
(463, 467) (487, 491) (499, 503) (613, 617) (643, 647) (673, 677)
(739, 743) (757, 761) (769, 773) (823, 827) (853, 857) (859, 863)
(877, 881) (883, 887) (907, 911) (937, 941) (967, 971)
There are 41 cousin primes less than 1000.
</pre>
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