A272628 Primes p such that (p^2 + p + 1)/7 is prime.

11, 23, 53, 179, 233, 317, 389, 401, 443, 599, 641, 683, 977, 1019, 1061, 1187, 1229, 1409, 1481, 1523, 1619, 1787, 1997, 2069, 2111, 2657, 2963, 3299, 3329, 3371, 3413, 3593, 3677, 3719, 4139, 4421, 4463, 5009, 5147, 5189, 5231, 5303, 5387, 5693

Offset

1,1

Comments

Primes in A002641.

Links

Seiichi Manyama, Table of n, a(n) for n = 1..1000

Example

a(1) = 11 because (11^2+11+1)/7 = 19 is a prime.

Mathematica

Select[Prime[Range[5000]], PrimeQ[(#^2 + # + 1) / 7] &]

Prog

(PARI) lista(nn) = {forprime(p=2, nn, if ((denominator(q=(p^2 + p + 1)/7) == 1) && isprime(q), print1(p, ", ")); ); } \\ Michel Marcus, May 05 2016

Crossrefs

Cf. A002641.

Sequence in context: A217566 A347141 A278869 * A141093 A041236 A097485

Adjacent sequences: A272625 A272626 A272627 * A272629 A272630 A272631

Keyword

nonn

Author

Vincenzo Librandi, May 04 2016

Status

approved