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

1,1

Comments

a(21) > 10^5.

Links

Table of n, a(n) for n=1..20.

Example

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A212019 A075708 A066617 * A024589 A062015 A006640

Adjacent sequences: A272269 A272270 A272271 * A272273 A272274 A272275

Keyword

nonn,more

Author

Robert Price, Apr 24 2016

Extensions

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

Status

approved