A272272 Numbers k such that 4^k-3^(k+1) is prime.

4, 8, 24, 36, 48, 246, 608, 734, 774, 824, 948, 1244, 3230, 4656, 5448, 6360, 7598, 15390, 48158, 86754

Offset: 1

Author

Robert Price, Apr 24 2016

Keywords

• nonn
• more

Comments

a(21) > 10^5.

Examples

			8 is a member since 4^8 - 3^9 = 65536-19683 = 45853 which is a prime number.
		

Crossrefs

Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883.

Programs

Mathematica

Select[Range[4, 100000], PrimeQ[4^# - 3^(# + 1)] &]

PARI

lista(nn) = for(n=1, nn, if(ispseudoprime(4^n-3^(n+1)), print1(n, ", "))); \\ Altug Alkan, Apr 24 2016

Extensions

Typo in a(11) corrected by Georg Fischer, Mar 19 2022