OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1687
FORMULA
a(n) = [x^n] ((x^6-1)/(x-1))^n.
a(n) <= A088218(n) with equality only for n < 6.
a(n) = Sum_{k=0..floor(n/6)} (-1)^k * binomial(n,k) * binomial(2*n-6*k-1,n-6*k). - Ilya Gutkovskiy, Nov 03 2021
MAPLE
b:= proc(n, i) option remember; `if`(n=0, 1,
`if`(i=0, 0, add(b(n-j, i-1), j=0..min(n, 5))))
end:
a:= n-> b(n$2):
seq(a(n), n=0..30);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Aug 17 2018
STATUS
approved