A320204 Number of sets of nonempty words with a total of n letters over ternary alphabet such that all letters occur at least once in the set.

13, 105, 588, 2811, 12354, 51543, 207846, 818241, 3165036, 12078462, 45602379, 170665569, 633997185, 2340201492, 8589679914, 31370151073, 114045173001, 412880470680, 1489008227689, 5350719651144, 19163305147338, 68416338358689, 243533302332309, 864441624894750

Offset

3,1

Links

Alois P. Heinz, Table of n, a(n) for n = 3..1000

Maple

h:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0,
      add(h(n-i*j, i-1, k)*binomial(k^i, j), j=0..n/i)))
    end:
a:= n-> (k-> add((-1)^i*binomial(k, i)*h(n$2, k-i), i=0..k))(3):
seq(a(n), n=3..30);

Crossrefs

Column k=3 of A319501.

Cf. A320213.

Sequence in context: A316613 A316425 A317427 * A080422 A030055 A155636

Adjacent sequences: A320201 A320202 A320203 * A320205 A320206 A320207

Keyword

nonn

Author

Alois P. Heinz, Oct 07 2018

Status

approved