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A272628 Primes p such that (p^2 + p + 1)/7 is prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A066179 A217566 A278869 * A141093 A041236 A097485

Adjacent sequences:  A272625 A272626 A272627 * A272629 A272630 A272631

KEYWORD

nonn

AUTHOR

Vincenzo Librandi, May 04 2016

STATUS

approved

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Last modified September 19 15:09 EDT 2020. Contains 337178 sequences. (Running on oeis4.)