cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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.

Original entry on oeis.org

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

Views

Author

Alois P. Heinz, Sep 03 2015

Keywords

Comments

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

Crossrefs

Column k=3 of A261835.

Programs

  • Maple
    b:= proc(n, i, p) option remember;
          `if`(i*(i+1)/2n, 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);