A096185 Numbers k such that 7^k + 6^(k-1) is prime.

3, 4, 8, 9, 16, 25, 33, 40, 116, 201, 208, 504, 579, 964, 1060, 1160, 1508, 1969, 4615, 7311, 65964, 83121, 87396

Offset: 1

Author

Herman H. Rosenfeld (herm3(AT)pacbell.net) and Robert G. Wilson v, Jun 18 2004

Keywords

• nonn
• more

Comments

a(24) > 10^5. - Robert Price, Mar 23 2016

Crossrefs

Cf. A082103, A093717, A093793, A093765, A093794, A093795, A096186.

Programs

Mathematica

Do[ If[ PrimeQ[7^n + 6^(n - 1)], Print[n]], {n, 4000}]

PARI

lista(nn) = {for(n=1, nn, if(ispseudoprime(7^n+6^(n-1)), print1(n, ", "))); } \\ Altug Alkan, Mar 23 2016

Extensions

a(19)-a(23) from Robert Price, Mar 23 2016