OFFSET
1,2
COMMENTS
If k belongs to this sequence, then so does (2^(k^2)+1)/k^2.
From Alexander Adamchuk, May 14 2010: (Start)
3 divides a(n) for n>1.
19 divides a(n) for n>2. (End)
LINKS
ArtOfProblemSolving forum, n^3 | (2^{n^2}+1)
MATHEMATICA
Select[Range[100000], Divisible[2^(#^2) + 1, #^3] &] (* Robert Price, Mar 23 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Alekseyev, Mar 27 2007, Mar 29 2007, Apr 18 2007
EXTENSIONS
a(7) from Ryan Propper, Jan 01 2008
a(8)-a(19) from Max Alekseyev, May 14 2010
STATUS
approved