OFFSET
4,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 4..803
FORMULA
a(n) = [x^n y^4] Product_{j>=1} 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 or i=1, x^n,
add(binomial(g(i)+j-1, j)*b(n-i*j, i-1)*x^j, j=0..n/i)), x, 5)
end:
a:= n-> coeff(b(n$2), x, 4):
seq(a(n), n=4..35);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Oct 21 2017
STATUS
approved