cp's OEIS Frontend

A320207 Number of sets of nonempty words with a total of n letters over senary alphabet such that all letters occur at least once in the set.

%I A320207 #7 Oct 07 2018 14:46:14
%S A320207 4051,111396,1830822,23420022,257667120,2564003346,23761098837,
%T A320207 208907298660,1764392910027,14440938630576,115269796672350,
%U A320207 901599089475150,6935143271107130,52608326918749428,394424679767297550,2927811687630339744,21547773469006784856
%N A320207 Number of sets of nonempty words with a total of n letters over senary alphabet such that all letters occur at least once in the set.
%H A320207 Alois P. Heinz, <a href="/A320207/b320207.txt">Table of n, a(n) for n = 6..1000</a>
%p A320207 h:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
%p A320207       add(h(n-i*j, i-1, k)*binomial(k^i, j), j=0..n/i)))
%p A320207     end:
%p A320207 a:= n-> (k-> add((-1)^i*binomial(k, i)*h(n$2, k-i), i=0..k))(6):
%p A320207 seq(a(n), n=6..25);
%Y A320207 Column k=6 of A319501.
%Y A320207 Cf. A320216.
%K A320207 nonn
%O A320207 6,1
%A A320207 _Alois P. Heinz_, Oct 07 2018