A253142 Numbers n such that n + 15 and n^2 + 15 are prime.
2, 4, 8, 14, 16, 22, 26, 32, 38, 44, 46, 52, 64, 68, 86, 88, 98, 124, 134, 158, 178, 184, 196, 212, 236, 242, 248, 256, 262, 296, 298, 316, 322, 338, 364, 374, 386, 394, 452, 472, 484, 488, 548, 578, 586, 598, 602, 626, 632, 638, 646, 658, 662, 676, 694, 718, 728, 736, 794, 806, 842, 848, 862
Offset: 1
Keywords
Examples
2 + 15 = 17 and 2^2 + 15 = 19 are both prime, so 2 is in the sequence.
Links
- Robert Israel, Table of n, a(n) for n = 1..10000
Programs
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Maple
select(t -> isprime(t+15) and isprime(t^2+15), [seq(i,i=2..1000,2)]); # Robert Israel, May 07 2019
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Mathematica
p = 15; Select[Range[2,1000,2], PrimeQ[p + #^2] && PrimeQ[p + #] &] Select[Range[2,1000,2],AllTrue[{#,#^2}+15,PrimeQ]&] (* Harvey P. Dale, Jun 08 2023 *)
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