OFFSET
0,1
LINKS
Eric M. Schmidt, Table of n, a(n) for n = 0..11
C. L. Stewart, On Divisors of Fermat, Fibonacci, Lucas, and Lehmer Numbers, Proceedings of the London Mathematical Society, Vol. s3-35, No. 3 (1977), pp. 425-447. See p. 430.
Eric Weisstein's World of Mathematics, Fermat Number.
FORMULA
From Amiram Eldar, Oct 25 2024: (Start)
a(n) > c * n * 2^n for n >= 1, where c is a positive absolute constant (Stewart, 1977). (End)
PROG
(PARI) a(n) = vecmax(factor(2^(2^n) + 1)[, 1]); \\ Michel Marcus, Jul 05 2017
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Benoit Cloitre, May 12 2002
EXTENSIONS
Offset changed by Arkadiusz Wesolowski, Jul 09 2011
STATUS
approved