OFFSET
0,3
COMMENTS
FORMULA
G.f.: exp(2*Sum_{k>=1} (sigma_1(k) - 1)*x^k/k). - Ilya Gutkovskiy, Aug 21 2018
a(n) ~ exp(2*Pi*sqrt(n/3)) * Pi^2 / (4 * 3^(7/4) * n^(9/4)). - Vaclav Kotesovec, Aug 21 2018
EXAMPLE
A000990 = (1, 1, 3, 5, 10, 16, ...). Pairwise differences = (1, 0, 2, 2, 5, ...).
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Nov 11 2008
EXTENSIONS
Definition changed and more terms added by Olivier Gérard, Jul 25 2016
STATUS
approved