Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #8 Nov 14 2019 12:59:20
%S 5,13,97,2070241,4338014017,3512911982806776822251393039617,
%T 4457915690803004131256192897205630962697827851093882159977969339137,
%U 1638935311392320153195136107636665419978585455388636669548298482694235538906271958706896595665141002450684974003603106305516970574177405212679151205373697500164072550932748470956551681
%N Smallest generalized Fermat prime of the form a^(2^n) + b^(2^n), where bases a,b>1; or -1 if no such prime exists.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GeneralizedFermatNumber.html">Generalized Fermat Number</a>.
%t Do[f=Min[Select[Take[Union[ Flatten[ Table[ i^(2^n) + j^(2^n), {i, 2, 300}, {j, 2, 300} ] ] ],500],PrimeQ]];Print[{n,f}],{n,0,7}]
%Y Cf. A000215 (Fermat numbers: 2^(2^n) + 1), A019434 (Fermat primes of the form 2^(2^n) + 1).
%Y Cf. A111635 (allows one of a,b to be 1).
%K nonn
%O 0,1
%A _Alexander Adamchuk_, Nov 14 2006
%E Offset corrected by _Jeppe Stig Nielsen_, Nov 14 2019