A186112 Numbers k such that 3*6^k + 1 is prime.

1, 2, 4, 6, 7, 8, 11, 15, 26, 29, 50, 66, 122, 225, 272, 275, 308, 390, 992, 1201, 2520, 15812, 17419, 29328, 41852

Offset

1,2

Comments

The primes produced by these values of n are in A186105.

Links

Table of n, a(n) for n=1..25.

Example

15 is in the sequence because 3*6^15+1=1410554953729 is prime.

Prog

(PARI) select(n->ispseudoprime(3*6^n+1), vector(10^4, i, i)) \\ Charles R Greathouse IV, Feb 13 2011
(PFGW) ABC2 3*6^$a+1
a: from 1 to 50000

Crossrefs

Sequence in context: A092054 A334573 A228370 * A029453 A330943 A352089

Adjacent sequences: A186109 A186110 A186111 * A186113 A186114 A186115

Keyword

nonn

Author

Gilbert Mozzo, Feb 12 2011

Extensions

a(14), a(15), a(17) added by D. S. McNeil, Feb 12 2011

a(20)-a(25) from Charles R Greathouse IV, Feb 13 2011 to Feb 14 2011

Status

approved