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A320205 Number of sets of nonempty words with a total of n letters over quaternary alphabet such that all letters occur at least once in the set. 3
73, 976, 8416, 59488, 375698, 2209276, 12376430, 66974912, 353260192, 1827146732, 9306483104, 46822023764, 233203697318, 1151770103264, 5647971709608, 27525892585476, 133427763556914, 643682934370820, 3091947949892804, 14794516505019096, 70537743010768506 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..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))(4):

seq(a(n), n=4..30);

CROSSREFS

Column k=4 of A319501.

Cf. A320214.

Sequence in context: A254136 A123811 A057522 * A305549 A320214 A346642

Adjacent sequences:  A320202 A320203 A320204 * A320206 A320207 A320208

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Oct 07 2018

STATUS

approved

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Last modified October 7 14:13 EDT 2022. Contains 357271 sequences. (Running on oeis4.)