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.
a(1) = (3-2)^2*3^2 =9.
a := proc(n) if isprime(2^(2^n)+1) then return (2^(2*2^n)-1)^2 fi; end; [seq(a(n),n=0..4)];
a(1) = 3^2 = 9. The spectral basis of A330826(1) = 12 is {9,4}, consisting of primes and powers.
F := n -> 2^(2^n) + 1; a := proc(n) if isprime(F(n)) then return F(n)^2 fi; end; [seq(a(n)),n=0..4)];
(2^2^Select[Range[0,5],PrimeQ[2^(2^#)+1] &]+1)^2 (* Stefano Spezia, May 01 2025 *)
a(0) = (3^2 - 1)^2 = 64.
F := proc(n) return 2^(2^n)+1 end; a := proc(n) if isprime(F(n)) then return (F(n)^2-1)^2 fi; end; [seq(a(n),n=0..4)];
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