Cousin primes: Difference between revisions

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=={{header|Seed7}}==

<lang seed7>$ include "seed7_05.s7i";

const func boolean: isPrime (in integer: number) is func

result

var boolean: prime is FALSE;

local

var integer: upTo is 0;

var integer: testNum is 3;

begin

if number = 2 then

prime := TRUE;

elsif odd(number) and number > 2 then

upTo := sqrt(number);

while number rem testNum <> 0 and testNum <= upTo do

testNum +:= 2;

end while;

prime := testNum > upTo;

end if;

end func;

const proc: main is func

local

var integer: n is 0;

var integer: count is 0;

begin

for n range 7 to 999 step 2 do

if isPrime(n) and isPrime(n - 4) then

writeln(n - 4 lpad 3 <& ", " <& n lpad 3);

incr(count);

end if;

end for;

writeln("\n" <& count <& " cousin prime pairs found < 1000.");

end func;</lang>

{{out}}

<pre style="height:14em">

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 cousin prime pairs found < 1000.