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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. 2
9, 225, 65025, 4294836225, 18446744065119617025 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The second element of the power-spectral basis of A330829 is A330831. We also have a(n) = (2^(2*2^n)-1)^2.

LINKS

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

FORMULA

a(n) = (A019434(n)-2)^2*A019434(n)^2.

EXAMPLE

a(1) = (3-2)^2*3^2  =9.

MAPLE

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)];

CROSSREFS

Cf. A000215, A001146, A019434, A330828.

Sequence in context: A095363 A138564 A285985 * A218536 A211048 A327146

Adjacent sequences:  A330827 A330828 A330829 * A330831 A330832 A330833

KEYWORD

nonn,hard

AUTHOR

Walter Kehowski, Jan 06 2020

STATUS

approved

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Last modified August 8 19:29 EDT 2020. Contains 336298 sequences. (Running on oeis4.)