A320208 Number of sets of nonempty words with a total of n letters over septenary alphabet such that all letters occur at least once in the set.

37633, 1366057, 28969248, 470004045, 6470660266, 79706067707, 906335330250, 9706198156760, 99243640018075, 978284068984075, 9363362648969343, 87485517250169934, 801259222264152813, 7216852772737393058, 64088034265985397794, 562287261308092526759

Offset: 7

Author

Alois P. Heinz, Oct 07 2018

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 7..1000

Crossrefs

Column k=7 of A319501.

Cf. A320217.

Programs

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))(7):
seq(a(n), n=7..25);