OFFSET
0,5
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: 1/(1 - sum(k>=1, k * x^(k^2)) ).
MAPLE
a:= proc(n) option remember; `if`(n=0, 1, `if`(n<0, 0,
add(k*a(n-k^2), k=1..isqrt(n))))
end:
seq(a(n), n=0..50); # Alois P. Heinz, Aug 04 2014
MATHEMATICA
a[n_] := a[n] = If[n == 0, 1, If[n<0, 0, Sum[k*a[n-k^2], {k, Sqrt[n]}]]];
Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Aug 29 2021, after Alois P. Heinz *)
PROG
(PARI) N=66; x='x+O('x^N); Vec(1/(1 - sum(k=1, 1+sqrtint(N), k * x^(k^2))) )
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Aug 04 2014
STATUS
approved