cp's OEIS Frontend

A261846 Number of compositions of n into distinct parts where each part i is marked with a word of length i over an octonary alphabet whose letters appear in alphabetical order.

%I A261846 #4 Sep 03 2015 07:52:14
%S A261846 1,8,36,696,2250,14712,245508,737352,3644355,17376832,325225824,
%T A261846 823612736,3820113552,14264475648,66782014272,1254553664640,
%U A261846 2949123559125,12008271483720,41150373332932,157262062899640,608878151760410,12804954311547288,27181470392583156
%N A261846 Number of compositions of n into distinct parts where each part i is marked with a word of length i over an octonary alphabet whose letters appear in alphabetical order.
%C A261846 Also matrices with eight rows of nonnegative integers with distinct positive column sums and total element sum n.
%H A261846 Alois P. Heinz, <a href="/A261846/b261846.txt">Table of n, a(n) for n = 0..5000</a>
%p A261846 b:= proc(n, i, p) option remember;
%p A261846       `if`(i*(i+1)/2<n, 0, `if`(n=0, p!, b(n, i-1, p)+
%p A261846       `if`(i>n, 0, b(n-i, i-1, p+1)*binomial(i+7, 7))))
%p A261846     end:
%p A261846 a:= n-> b(n$2, 0):
%p A261846 seq(a(n), n=0..25);
%Y A261846 Column k=8 of A261835.
%K A261846 nonn
%O A261846 0,2
%A A261846 _Alois P. Heinz_, Sep 03 2015