OFFSET
9,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 9..60
MAPLE
h:= proc(l) local n; n:= nops(l); add(i, i=l)! /mul(mul(1+l[i]-j
+add(`if`(l[k]>=j, 1, 0), k=i+1..n), j=1..l[i]), i=1..n) end:
g:= (n, i, l)-> `if`(n=0 or i=1, h([l[], 1$n])^2, `if`(i<1, 0,
add(g(n-i*j, i-1, [l[], i$j]), j=0..n/i))):
a:= n-> g(n-9, min(n-9, 9), [9]):
seq(a(n), n=9..30);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jul 28 2014
STATUS
approved