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
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, May 04 2016
STATUS
approved