A302123 Numbers k such that 6*k^k - 5 is prime.

2, 3, 4, 7, 8, 9, 33, 138, 251, 467, 489, 9894

Offset

1,1

Comments

a(13) > 50000. - Robert Price, Jan 04 2020

Links

Table of n, a(n) for n=1..12.

Mathematica

Select[Range[1, 1000], PrimeQ[6*#^# - 5] &] (* Vaclav Kotesovec, Apr 02 2018 *)

Prog

(PARI) for(n=0, 300, if(isprime(6*n^n-5), print1(n", ")))

Crossrefs

Numbers k such that b*k^k - b + 1 is prime: A301521 (b=4), this sequence (b=6).

Cf. A302090, A302124.

Sequence in context: A111116 A113318 A056033 * A286337 A047547 A014456

Adjacent sequences: A302120 A302121 A302122 * A302124 A302125 A302126

Keyword

nonn,more,hard

Author

Seiichi Manyama, Apr 01 2018

Extensions

a(10)-a(11) from Vaclav Kotesovec, Apr 02 2018

a(12) from Robert Price, Jan 04 2020

Status

approved