A243478 - OEIS

%I #7 Feb 09 2015 10:34:04

%S 22,1546,46947,944701,14745521,193273378,2228848403,23305050081,

%T 225560761204,2051114040040,17719591217257,146674616051322,

%U 1171101886353096,9067551569835697,68378670584901547,504001041740002317,3641720452674969516,25859746275607624792

%N Number of isoscent sequences of length n with exactly five descents.

%H Joerg Arndt and Alois P. Heinz, <a href="/A243478/b243478.txt">Table of n, a(n) for n = 10..100</a>

%t b[n_, i_, t_] := b[n, i, t] = If[n < 1, 1, Expand[Sum[ If[j < i, x, 1] *b[n - 1, j, t + If[j == i, 1, 0]], {j, 0, t + 1}]]]; a[n_] := Coefficient[b[n - 1, 0, 0], x, 5]; Table[a[n], {n, 10, 40}] (* _Jean-François Alcover_, Feb 09 2015, after A242352 *)

%Y Column k=5 of A242352.

%K nonn

%O 10,1

%A _Joerg Arndt_ and _Alois P. Heinz_, Jun 05 2014