A261845 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a septenary alphabet whose letters appear in alphabetical order.

1, 7, 28, 476, 1386, 8106, 117936, 322764, 1440579, 6172495, 99773646, 232110704, 981073576, 3329628176, 14040114012, 224848217580, 490210909629, 1828885568055, 5750093241172, 20040621544916, 69910543160794, 1238596672832718, 2451410591056280, 8705347941656016

Offset

0,2

Comments

Also matrices with seven 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+6, 6))))
    end:
a:= n-> b(n$2, 0):
seq(a(n), n=0..25);

Crossrefs

Column k=7 of A261835.

Sequence in context: A203209 A193288 A050548 * A181942 A140447 A038934

Adjacent sequences: A261842 A261843 A261844 * A261846 A261847 A261848

Keyword

nonn

Author

Alois P. Heinz, Sep 03 2015

Status

approved