OFFSET
0,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
G. E. Andrews, Some debts I owe, Séminaire Lotharingien de Combinatoire, Paper B42a, Issue 42, 2000; see (7.4).
FORMULA
a(n) = (sigma(n)+tau(n)+Sum_{k=0..n} tau(k)*tau(n-k))/2.
G.f.: (F(x)+G(x)^2)/2, where F(x) = Sum_{k>0} (k+1)*x^k/(1-x^k) and G(x) = Sum_{k>0} x^k/(1-x^k). - Vladeta Jovovic, Feb 12 2004
MAPLE
Mk := proc(k) -1*add( (-1)^n*q^(n*(n+1)/2)/(1-q^n)^k/mul(1-q^i, i=1..n), n=1..101): end; # with k=2
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Feb 24 2001
STATUS
approved