A098876 Least k such that 3*((6*n)^k) - 1 is prime.

1, 2, 1, 1, 1, 1, 2523, 2, 2, 1, 1, 2, 1, 1, 1, 2, 3, 6, 63, 1, 50, 38, 2, 1, 1, 1, 79, 1, 1, 3, 1, 4, 1, 2, 2, 1, 6, 1, 1, 1, 5, 3, 1, 18, 1, 1, 11, 1, 1, 26, 3, 10, 1, 1, 4, 2, 2, 4, 1, 6, 1, 4, 54, 1, 10, 1, 3, 1, 2, 1, 1

Offset: 1

Author

Pierre CAMI, Oct 13 2004

Keywords

• nonn

Comments

a(72) > 3830, and the sequence then continues: 6, 2, 7, 1, 27, 2, 3, 1, 7, 2, 1, 1, 4, 36, 346, 1, 1, 1, 1, 3, 6, 2, 1, 2, 444, ...

a(72) > 10^4. - Ray Chandler, Nov 13 2004

Crossrefs

Cf. A098877, A138918.

Programs

Mathematica

f[n_] := Block[{k = 1}, While[ !PrimeQ[3*((6*n)^k) - 1], k++ ]; k]; Table[ f[n], {n, 71}] (* Robert G. Wilson v, Oct 21 2004 *)

Formula

a(A138918(n)) = 1. - Michel Marcus, Jul 28 2015

Extensions

Corrected and extended by Robert G. Wilson v, Oct 22 2004