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.

A261843 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a quinary alphabet whose letters appear in alphabetical order.

Original entry on oeis.org

1, 5, 15, 185, 420, 1876, 19320, 42610, 149115, 495205, 5516001, 10570145, 35897010, 97383790, 320607680, 3412039628, 6292069835, 19106603405, 49239854095, 138462457915, 378598491878, 4312038483490, 7316190877970, 21527078513430, 50933081112485
Offset: 0

Views

Author

Alois P. Heinz, Sep 03 2015

Keywords

Comments

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

Crossrefs

Column k=5 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+4, 4))))
        end:
    a:= n-> b(n$2, 0):
    seq(a(n), n=0..30);