A330831 a(n) = (F_n^2 - 1)^2, where F_n is a Fermat prime, A019434.

64, 576, 82944, 4362338304, 18447869990796263424

Offset

1,1

Comments

Also the second element of the power-spectral basis of A330829.

The first element of the power-spectral basis of A330829 is A330830.

Links

Table of n, a(n) for n=1..5.

Formula

a(n) = (F(n)^2 - 1)^2, where F(n) = 2^(2^n)+1 is a Fermat prime.

Example

a(0) = (3^2 - 1)^2 = 64.

Maple

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)];

Crossrefs

Cf. A000215, A001146, A019434, A330827, A330828, A330829, A330830.

Sequence in context: A209787 A247841 A209780 * A177757 A301796 A301969

Adjacent sequences: A330828 A330829 A330830 * A330832 A330833 A330834

Keyword

nonn

Author

Walter Kehowski, Jan 06 2020

Status

approved