OFFSET
5,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 5..803
FORMULA
a(n) = [x^n y^3] Product_{j>=1} (1+y*x^j)^A000085(j).
MAPLE
g:= proc(n) option remember; `if`(n<2, 1, g(n-1)+(n-1)*g(n-2)) end:
b:= proc(n, i) option remember; series(`if`(n=0, 1, `if`(i<1, 0,
add(b(n-i*j, i-1)*binomial(g(i), j)*x^j, j=0..n/i))), x, 4)
end:
a:= n-> coeff(b(n$2), x, 3):
seq(a(n), n=5..30);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 20 2017
STATUS
approved