cp's OEIS Frontend

A241694 Number of Carlitz compositions of n with exactly four descents.

%I A241694 #6 Apr 28 2014 09:30:00
%S A241694 5,22,72,204,510,1168,2516,5140,10054,18976,34707,61776,107374,182697,
%T A241694 304982,500455,808462,1287499,2023697,3142604,4825797,7333862,
%U A241694 11037829,16462497,24345385,35716339,52005295,75186849,107973181,154071381,218524581,308162131
%N A241694 Number of Carlitz compositions of n with exactly four descents.
%C A241694 No two adjacent parts of a Carlitz composition are equal.
%H A241694 Alois P. Heinz, <a href="/A241694/b241694.txt">Table of n, a(n) for n = 12..1000</a>
%p A241694 b:= proc(n, i) option remember; `if`(n=0, 1,
%p A241694        convert(series(add(`if`(i=j, 0, b(n-j, j)*
%p A241694       `if`(j<i, x, 1)), j=1..n), x, 5), polynom))
%p A241694     end:
%p A241694 a:= n-> coeff(b(n, 0), x, 4):
%p A241694 seq(a(n), n=12..50);
%Y A241694 Column k=4 of A241701.
%K A241694 nonn
%O A241694 12,1
%A A241694 _Alois P. Heinz_, Apr 27 2014