A261840 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a binary alphabet whose letters appear in alphabetical order.

1, 2, 3, 16, 21, 50, 205, 292, 587, 1110, 4535, 5980, 12447, 20910, 40195, 142520, 196291, 372042, 635081, 1128872, 1873245, 6537466, 8553639, 16333532, 26470861, 46629886, 73222631, 127947300, 385293581, 518212198, 939401193, 1516760160, 2564361235

Offset: 0

Author

Alois P. Heinz, Sep 03 2015

Keywords

• nonn

Comments

Also matrices with two 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

Crossrefs

Column k=2 of A261835.

Programs

Maple

b:= proc(n, i, p) option remember;
      `if`(i*(i+1)/2n, 0, b(n-i, i-1, p+1)*(i+1))))
    end:
a:= n-> b(n$2, 0):
seq(a(n), n=0..40);