OFFSET
0,1
COMMENTS
REFERENCES
Michal Krížek, Florian Luca and Lawrence Somer, 17 Lectures on Fermat Numbers, Springer-Verlag, N.Y., 2001, p. 142.
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..10
Andrzej Rotkiewicz, On pseudoprimes having special forms and a solution of K. Szymiczek's problem, Acta Mathematica Universitatis Ostraviensis, Vol. 13, No. 1 (2005), pp. 57-71.
Kazimierz Szymiczek, Note on Fermat numbers, Elemente der Mathematik, Vol. 21, No. 3 (1966), p. 59.
FORMULA
a(n) = (2^(2^n) + 1) * (2^(2^(n+1)) + 1).
MATHEMATICA
f[n_] := 2^(2^n) + 1; a[n_] := f[n] * f[n + 1]; Array[a, 7, 0]
PROG
(PARI) f(n) = 2^(2^n) + 1;
a(n) = f(n) * f(n+1);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amiram Eldar, Nov 11 2023
STATUS
approved