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%I #5 Oct 07 2018 14:41:44
%S 73,1028,9182,66584,428653,2557972,14496714,79179724,420817947,
%T 2190356332,11216217292,56689332604,283477764373,1404999644584,
%U 6911375241384,33778491898132,164157640596783,793799200891568,3821351207383146,18321693995577480,87520485093330489
%N Number of multisets of nonempty words with a total of n letters over quaternary alphabet such that all letters occur at least once in the multiset.
%H Alois P. Heinz, <a href="/A320214/b320214.txt">Table of n, a(n) for n = 4..1000</a>
%p b:= proc(n, k) option remember; `if`(n=0, 1, add(add(
%p d*k^d, d=numtheory[divisors](j))*b(n-j, k), j=1..n)/n)
%p end:
%p a:= n-> (k-> add(b(n, k-i)*(-1)^i*binomial(k, i), i=0..k))(4):
%p seq(a(n), n=4..25);
%Y Column k=4 of A257740.
%Y Cf. A320205.
%K nonn
%O 4,1
%A _Alois P. Heinz_, Oct 07 2018
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