A378134 - OEIS

%I #15 Dec 03 2024 12:42:20

%S 2,2,2,2,37,281,137,2129,139,23,1231,1279,17477

%N a(n) is the smallest prime p such that (2*p)^(2^n) + 1 is also prime.

%Y Primes p such that (2*p)^(2^k) + 1 is prime: A005384 (k = 0), A052291 (k = 1), A378146 (k = 2).

%Y If a(n) is the smallest prime number p such that (p*2^m)^(2^n) + 1, then we have:

%Y 2, 2, 2, 2, 2 (in case m = 0), where primes of the form (p*2^0)^(2^n)+1 are A019434;

%Y this sequence (in case m = 1).

%Y Cf. A378143.

%K nonn,more

%O 0,1

%A _Juri-Stepan Gerasimov_, Nov 17 2024

%E a(11)-a(12) from _Michael S. Branicky_, Nov 18 2024