A229891 - OEIS

%I #9 Oct 04 2013 07:44:22

%S 1,1,1,1,1,1,1,1,1,1,1,1,11,66,286,1001,3003,8008,19448,43758,92378,

%T 184756,3711916,39277446,290971966,1693270006,8237327526,34822561201,

%U 131333661601,450356465701,1424215551901,4199713947571,122741742741301,1863639732429616

%N Number of 10 up, 10 down permutations of [n].

%H Alois P. Heinz, <a href="/A229891/b229891.txt">Table of n, a(n) for n = 0..200</a>

%p b:= proc(u, o, t) option remember; `if`(u+o=0, 1, add(`if`(t=10,

%p        b(o-j, u+j-1, 1), b(u+j-1, o-j, t+1)), j=1..o))

%p     end:

%p a:= n-> b(0, n, 0):

%p seq(a(n), n=0..35);

%Y Column k=10 of A229892.

%K nonn,eigen

%O 0,13

%A _Alois P. Heinz_, Oct 02 2013