A087091 Numbers k such that p = k^2 + k + 41 and p - 2 are twin primes.
1, 4, 10, 16, 19, 31, 34, 43, 55, 58, 61, 70, 73, 79, 85, 94, 100, 118, 148, 154, 160, 175, 196, 199, 211, 214, 223, 226, 229, 238, 253, 274, 313, 340, 424, 430, 469, 499, 508, 529, 538, 541, 550, 565, 640, 658, 673, 706, 724, 760, 763, 781
Offset: 1
Keywords
Examples
4 is in the sequence because 61 = 4^2 + 4 + 41 and 59 are twin primes.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Select[Range[10^3], And @@ PrimeQ[#^2 + # + {39, 41}] &] (* Amiram Eldar, Dec 27 2019 *) -
PARI
isok(n) = isprime(n^2+n+41) && isprime(n^2+n+39); \\ Michel Marcus, Oct 03 2013