OFFSET
0,6
LINKS
Alois P. Heinz and Vaclav Kotesovec, Table of n, a(n) for n = 0..1000 (terms 0..750 from Alois P. Heinz)
FORMULA
a(n) = [x^(n^2)] Product_{k>=1} (1 + x^(k^2)). - Ilya Gutkovskiy, Apr 13 2017
MAPLE
b:= proc(n, i) option remember; `if`(n=0, 1,
`if`(n>i*(i+1)*(2*i+1)/6, 0, b(n, i-1)+
`if`(i^2>n, 0, b(n-i^2, i-1))))
end:
a:= n-> b(n^2, n):
seq(a(n), n=0..50); # Alois P. Heinz, Nov 20 2012
MATHEMATICA
b[n_, i_] := b[n, i] = If[n==0, 1, If[n > i*(i+1)*(2*i+1)/6, 0, b[n, i-1] +If[i^2 > n, 0, b[n-i^2, i-1]]]]; a[n_] := b[n^2, n]; Table[a[n], {n, 0, 50}] (* Jean-François Alcover, Jul 30 2015, after Alois P. Heinz *)
PROG
(Haskell)
a030273 n = p (map (^ 2) [1..]) (n^2) where
p _ 0 = 1
p (k:ks) m | m < k = 0
| otherwise = p ks (m - k) + p ks m
-- Reinhard Zumkeller, Aug 14 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Feb 18 2015
STATUS
approved