A261841 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a ternary alphabet whose letters appear in alphabetical order.

1, 3, 6, 46, 75, 231, 1414, 2376, 5985, 14151, 89454, 135330, 343677, 697017, 1657212, 9439826, 14381055, 33119667, 66361286, 141451860, 283907499, 1642516411, 2346737106, 5367877296, 10093521943, 20923900623, 38428831710, 80538197724, 416229711735

Offset

0,2

Comments

Also matrices with three rows 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..5000

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+2, 2))))
    end:
a:= n-> b(n$2, 0):
seq(a(n), n=0..40);

Crossrefs

Column k=3 of A261835.

Sequence in context: A137775 A038050 A194080 * A197884 A279706 A032322

Adjacent sequences: A261838 A261839 A261840 * A261842 A261843 A261844

Keyword

nonn

Author

Alois P. Heinz, Sep 03 2015

Status

approved