This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A123646 #9 Feb 16 2025 08:33:03
%S A123646 5,13,97,2070241,4338014017,3512911982806776822251393039617,
%T A123646 4457915690803004131256192897205630962697827851093882159977969339137,
%U A123646 1638935311392320153195136107636665419978585455388636669548298482694235538906271958706896595665141002450684974003603106305516970574177405212679151205373697500164072550932748470956551681
%N A123646 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 A123646 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GeneralizedFermatNumber.html">Generalized Fermat Number</a>.
%t A123646 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 A123646 Cf. A000215 (Fermat numbers: 2^(2^n) + 1), A019434 (Fermat primes of the form 2^(2^n) + 1).
%Y A123646 Cf. A111635 (allows one of a,b to be 1).
%K A123646 nonn
%O A123646 0,1
%A A123646 _Alexander Adamchuk_, Nov 14 2006
%E A123646 Offset corrected by _Jeppe Stig Nielsen_, Nov 14 2019