Honaker primes: Difference between revisions
Added Forth solution
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(Added Forth solution) |
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{ 761 5801 } { 767 5843 } { 779 5927 } { 820 6301 } { 821 6311 }
{ 826 6343 } { 827 6353 } { 847 6553 } { 848 6563 } { 857 6653 }
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=={{header|Forth}}==
{{works with|Gforth}}
<syntaxhighlight lang="forth">: prime? ( n -- ? ) here + c@ 0= ;
: notprime! ( n -- ) here + 1 swap c! ;
: prime_sieve { n -- }
here n erase
0 notprime!
1 notprime!
n 4 > if
n 4 do i notprime! 2 +loop
then
3
begin
dup dup * n <
while
dup prime? if
n over dup * do
i notprime!
dup 2* +loop
then
2 +
repeat
drop ;
: digit_sum ( u -- u )
dup 10 < if exit then
10 /mod recurse + ;
: next_prime ( u -- u )
begin
1+ dup prime?
until ;
: next_honaker_prime ( u u -- u u )
begin
swap next_prime swap 1+
2dup digit_sum swap digit_sum =
until ;
: print_pair ( u u -- )
." (" 3 .r ." , " 4 .r ." )" ;
: main
5000000 prime_sieve
." First 50 Honaker primes (index, prime):" cr
0 0 0 \ prime prime-index honaker-index
begin
dup 50 <
while
-rot next_honaker_prime
2dup print_pair rot 1+
dup 5 mod 0= if cr else space then
repeat
begin
dup 10000 <
while
-rot next_honaker_prime rot 1+
repeat
drop
cr ." Ten thousandth: " print_pair ;
main cr bye</syntaxhighlight>
{{out}}
<pre>
First 50 Honaker primes (index, prime):
( 32, 131) ( 56, 263) ( 88, 457) (175, 1039) (176, 1049)
(182, 1091) (212, 1301) (218, 1361) (227, 1433) (248, 1571)
(293, 1913) (295, 1933) (323, 2141) (331, 2221) (338, 2273)
(362, 2441) (377, 2591) (386, 2663) (394, 2707) (397, 2719)
(398, 2729) (409, 2803) (439, 3067) (446, 3137) (457, 3229)
(481, 3433) (499, 3559) (508, 3631) (563, 4091) (571, 4153)
(595, 4357) (599, 4397) (635, 4703) (637, 4723) (655, 4903)
(671, 5009) (728, 5507) (751, 5701) (752, 5711) (755, 5741)
(761, 5801) (767, 5843) (779, 5927) (820, 6301) (821, 6311)
(826, 6343) (827, 6353) (847, 6553) (848, 6563) (857, 6653)
Ten thousandth: (286069, 4043749)
</pre>
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