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 A330830 #15 Jan 12 2020 13:43:50 %S A330830 9,225,65025,4294836225,18446744065119617025 %N A330830 Numbers of the form (F_n-2)^2*F_n^2, where F_n is a Fermat prime, A019434. Also the first element of the power-spectral basis of A330829. %C A330830 The second element of the power-spectral basis of A330829 is A330831. We also have a(n) = (2^(2*2^n)-1)^2. %F A330830 a(n) = (A019434(n)-2)^2*A019434(n)^2. %e A330830 a(1) = (3-2)^2*3^2 =9. %p A330830 a := proc(n) if isprime(2^(2^n)+1) then return (2^(2*2^n)-1)^2 fi; end; %p A330830 [seq(a(n),n=0..4)]; %Y A330830 Cf. A000215, A001146, A019434, A330828. %K A330830 nonn,hard %O A330830 1,1 %A A330830 _Walter Kehowski_, Jan 06 2020