A229891 Number of 10 up, 10 down permutations of [n].

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 66, 286, 1001, 3003, 8008, 19448, 43758, 92378, 184756, 3711916, 39277446, 290971966, 1693270006, 8237327526, 34822561201, 131333661601, 450356465701, 1424215551901, 4199713947571, 122741742741301, 1863639732429616

Offset

0,13

Links

Alois P. Heinz, Table of n, a(n) for n = 0..200

Maple

b:= proc(u, o, t) option remember; `if`(u+o=0, 1, add(`if`(t=10,
       b(o-j, u+j-1, 1), b(u+j-1, o-j, t+1)), j=1..o))
    end:
a:= n-> b(0, n, 0):
seq(a(n), n=0..35);

Crossrefs

Column k=10 of A229892.

Sequence in context: A008503 A008493 A001287 * A243745 A325752 A221143

Adjacent sequences: A229888 A229889 A229890 * A229892 A229893 A229894

Keyword

nonn,eigen

Author

Alois P. Heinz, Oct 02 2013

Status

approved