A199191 Numbers k such that 3^(2k-3) + 3^(k-1) + 1 is prime.

2, 3, 4, 5, 6, 10, 11, 41, 83, 160, 178, 526, 881, 2578, 3772, 11873

Offset: 1

Author

Michel Lagneau, Nov 03 2011

Keywords

• nonn
• hard
• more

Comments

Numbers k such that A198410(k) is prime.

Crossrefs

Cf. A198410, A199192.

Programs

Mathematica

Select[Range[250], PrimeQ[((3^(#-1) + 1)^3 -1)/3^#]&]

Extensions

a(16) from Michael S. Branicky, May 12 2023