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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. 3
13, 105, 588, 2811, 12354, 51543, 207846, 818241, 3165036, 12078462, 45602379, 170665569, 633997185, 2340201492, 8589679914, 31370151073, 114045173001, 412880470680, 1489008227689, 5350719651144, 19163305147338, 68416338358689, 243533302332309, 864441624894750 (list; graph; refs; listen; history; text; internal format)
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

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Last modified January 19 06:18 EST 2022. Contains 350464 sequences. (Running on oeis4.)