cp's OEIS Frontend

A261847 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a nonary alphabet whose letters appear in alphabetical order.

%I A261847 #4 Sep 03 2015 08:36:50
%S A261847 1,9,45,975,3465,25047,471669,1542519,8361540,43916950,934748298,
%T A261847 2560160538,12924414750,52656337800,271075650210,5853558884496,
%U A261847 14764118156523,65116959410547,241547985000289,1004388404964615,4276652360222781,104392134731727315
%N A261847 Number of compositions of n into distinct parts where each part i is marked with a word of length i over a nonary alphabet whose letters appear in alphabetical order.
%C A261847 Also matrices with two nine of nonnegative integers with distinct positive column sums and total element sum n.
%H A261847 Alois P. Heinz, <a href="/A261847/b261847.txt">Table of n, a(n) for n = 0..4921</a>
%p A261847 b:= proc(n, i, p) option remember;
%p A261847       `if`(i*(i+1)/2<n, 0, `if`(n=0, p!, b(n, i-1, p)+
%p A261847       `if`(i>n, 0, b(n-i, i-1, p+1)*binomial(i+8, 8))))
%p A261847     end:
%p A261847 a:= n-> b(n$2, 0):
%p A261847 seq(a(n), n=0..25);
%Y A261847 Column k=9 of A261835.
%K A261847 nonn
%O A261847 0,2
%A A261847 _Alois P. Heinz_, Sep 03 2015