cp's OEIS Frontend

A320213 Number of multisets of nonempty words with a total of n letters over ternary alphabet such that all letters occur at least once in the multiset.

%I A320213 #8 Oct 07 2018 14:39:06
%S A320213 13,114,672,3334,15030,63978,261880,1043658,4076856,15688108,59650623,
%T A320213 224625639,839026657,3112293273,11474908920,42080197859,153566261268,
%U A320213 557943898644,2018901838589,7277784002970,26142839723154,93599166705077,334072869753357
%N A320213 Number of multisets of nonempty words with a total of n letters over ternary alphabet such that all letters occur at least once in the multiset.
%H A320213 Alois P. Heinz, <a href="/A320213/b320213.txt">Table of n, a(n) for n = 3..1000</a>
%p A320213 b:= proc(n, k) option remember; `if`(n=0, 1, add(add(
%p A320213       d*k^d, d=numtheory[divisors](j))*b(n-j, k), j=1..n)/n)
%p A320213     end:
%p A320213 a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(3):
%p A320213 seq(a(n), n=3..30);
%Y A320213 Column k=3 of A257740.
%Y A320213 Cf. A320204.
%K A320213 nonn
%O A320213 3,1
%A A320213 _Alois P. Heinz_, Oct 07 2018