0,1

As for standard Fermat numbers 2^(2^n) + 1, a number b^m + 1 (with b > 1) can only be prime if m is a power of 2. On the other hand, out of the first 13 base-6 Fermat numbers, only the first three are primes.

There are only 5 known Fermat primes of the form 2^(2^n) + 1: {3, 5, 17, 257, 65537}. There are only 2 known base-10 generalized Fermat primes of the form 10^(2^n) + 1: {11, 101}. - Alexander Adamchuk (alex(AT)kolmogorov.com), Mar 17 2007

Eric Weisstein's World of Mathematics, Generalized Fermat Number.

a(0)=7, a(n) = (a(n-1)-1)^2 + 1

Cf. A078303, A080174 = Base-6 Fermat numbers: 6^(2^n) + 1. Cf. A000215 = Fermat numbers: 2^(2^n) + 1. Cf. A019434 = Fermat primes of the form 2^(2^n) + 1. Cf. A080176 = Base-10 Fermat numbers: 10^(2^n) + 1. Cf. A123669, A123599, A056993, A126032.

Cf. A000215, A019434, A080176.

Adjacent sequences: A080171 A080172 A080173 this_sequence A080175 A080176 A080177

Sequence in context: A097493 A082687 A117731 this_sequence A127729 A129736 A003352

easy,nonn

Jens Voss (jens(AT)voss-ahrensburg.de), Feb 04 2003

The next term is too large to include.