OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..500
FORMULA
G.f.: Sum_{n>=0}[(1-x^n)/(1-x)^n*Sum_{d|n}x^(n*d)].
a(n) ~ 2^(n-1). - Vaclav Kotesovec, May 01 2014
MAPLE
b:= proc(n, t, g) option remember; `if` (n=0, `if` (irem(t, g)=0, 1, 0), add (b(n-i, t+1, min(i, g)), i=1..n)) end: a:= n-> b(n, 0, infinity): seq (a(n), n=1..40); # Alois P. Heinz, Dec 15 2009
MATHEMATICA
a[n_] := SeriesCoefficient[ Sum[(1-x^k)/(1-x)^k*Sum[x^(k*d), {d, Divisors[k]}], {k, 0, n}], {x, 0, n}]; Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Feb 24 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Dec 13 2009
EXTENSIONS
More terms from Alois P. Heinz, Dec 15 2009
STATUS
approved