cp's OEIS Frontend

A320210 Number of sets of nonempty words with a total of n letters over nonary alphabet such that all letters occur at least once in the set.

%I A320210 #7 Oct 07 2018 14:52:48
%S A320210 4596553,263460321,8549512506,207037303758,4169086763787,
%T A320210 73865658618900,1191183607371897,17876336340787308,253521082577243286,
%U A320210 3435636331820210328,44859666267675306756,567955878004442678319,7007036376866803617768,84571686324119453047650
%N A320210 Number of sets of nonempty words with a total of n letters over nonary alphabet such that all letters occur at least once in the set.
%H A320210 Alois P. Heinz, <a href="/A320210/b320210.txt">Table of n, a(n) for n = 9..1000</a>
%p A320210 h:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
%p A320210       add(h(n-i*j, i-1, k)*binomial(k^i, j), j=0..n/i)))
%p A320210     end:
%p A320210 a:= n-> (k-> add((-1)^i*binomial(k, i)*h(n$2, k-i), i=0..k))(9):
%p A320210 seq(a(n), n=9..25);
%Y A320210 Column k=9 of A319501.
%Y A320210 Cf. A320219.
%K A320210 nonn
%O A320210 9,1
%A A320210 _Alois P. Heinz_, Oct 07 2018