A098873 Least k such that 2*((6*n)^k) - 1 is prime.

1, 1, 2, 1, 1, 1, 1, 4, 1, 5, 1, 34, 7, 1, 1, 1, 2, 2, 1, 1, 1, 1, 4, 24, 8, 1, 10, 7, 1, 1, 2, 1, 3, 2, 1, 1, 1, 2, 1, 1, 1, 1, 28, 5, 2, 2484, 1, 2, 1, 1

Offset: 1

Author

Pierre CAMI, Oct 13 2004

Keywords

• nonn

Examples

			2*((6*1)^1) - 1 = 11 prime, so a(1)=1
2*((6*2)^1) - 1 = 23 prime, so a(2)=1
2*((6*3)^1) - 1 = 35 = 5*7
2*((6*3)^2) - 1 = 647 prime, so a(3)=2
		

Programs

Mathematica

lk[n_]:=Module[{k=1},While[!PrimeQ[2((6n)^k)-1],k++];k]; Array[lk,50] (* Harvey P. Dale, Apr 02 2018 *)

Extensions

Corrected by Harvey P. Dale, Apr 02 2018