A217351 Numbers k such that 6^k + 7 is prime.

1, 2, 3, 4, 6, 21, 24, 27, 30, 54, 70, 126, 369, 435, 612, 787, 1275, 2155, 2436, 5734, 6016, 16107, 25786

Offset

1,2

Links

Table of n, a(n) for n=1..23.

Mathematica

Select[Range[10000], PrimeQ[6^# + 7] &]

Prog

(PARI) is(n)=ispseudoprime(6^n+7) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A145106, A217352.

Cf. A104115 (associated primes).

Sequence in context: A220702 A342503 A369773 * A274238 A115035 A219048

Adjacent sequences: A217348 A217349 A217350 * A217352 A217353 A217354

Keyword

nonn,more,hard

Author

Vincenzo Librandi, Oct 02 2012

Extensions

a(20)-a(21) from Bruno Berselli, Oct 04 2012

a(22)-a(23) from Michael S. Branicky, Apr 30 2023

Status

approved