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.

73, 976, 8416, 59488, 375698, 2209276, 12376430, 66974912, 353260192, 1827146732, 9306483104, 46822023764, 233203697318, 1151770103264, 5647971709608, 27525892585476, 133427763556914, 643682934370820, 3091947949892804, 14794516505019096, 70537743010768506

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