A261847 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a nonary alphabet whose letters appear in alphabetical order.

1, 9, 45, 975, 3465, 25047, 471669, 1542519, 8361540, 43916950, 934748298, 2560160538, 12924414750, 52656337800, 271075650210, 5853558884496, 14764118156523, 65116959410547, 241547985000289, 1004388404964615, 4276652360222781, 104392134731727315

Offset

0,2

Comments

Also matrices with two nine of nonnegative integers with distinct positive column sums and total element sum n.

Links

Alois P. Heinz, Table of n, a(n) for n = 0..4921

Maple

b:= proc(n, i, p) option remember;
      `if`(i*(i+1)/2<n, 0, `if`(n=0, p!, b(n, i-1, p)+
      `if`(i>n, 0, b(n-i, i-1, p+1)*binomial(i+8, 8))))
    end:
a:= n-> b(n$2, 0):
seq(a(n), n=0..25);

Crossrefs

Column k=9 of A261835.

Sequence in context: A322892 A355175 A352398 * A050909 A333306 A230062

Adjacent sequences: A261844 A261845 A261846 * A261848 A261849 A261850

Keyword

nonn

Author

Alois P. Heinz, Sep 03 2015

Status

approved