A229892 -id:A229892 - cp's OEIS frontend

A229889 Number of 8 up, 8 down permutations of [n].

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 45, 165, 495, 1287, 3003, 6435, 12870, 207350, 1782638, 10852478, 52422578, 213586658, 762311978, 2445069626, 7177825511, 167072419775, 2041472747275, 17401832788275, 116094500641665, 645070724513865, 3103383925397925

Offset: 0

Alois P. Heinz, Oct 02 2013

			a(9) = 1: 123456789.

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

Column k=8 of A229892.

b:= proc(u, o, t) option remember; `if`(u+o=0, 1, add(`if`(t=8,
       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);

A229890 Number of 9 up, 9 down permutations of [n].

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 10, 55, 220, 715, 2002, 5005, 11440, 24310, 48620, 880022, 8438222, 56936672, 303159572, 1354883102, 5281317614, 18427861739, 58640820239, 172577535989, 4529938877492, 62058701943644, 590100171030140, 4371834356234285

Offset: 0

Alois P. Heinz, Oct 02 2013

			a(9) = 1: 123456789.

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

Column k=9 of A229892.

b:= proc(u, o, t) option remember; `if`(u+o=0, 1, add(`if`(t=9,
       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);

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

Original entry on oeis.org

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

Alois P. Heinz, Oct 02 2013

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

Column k=10 of A229892.

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);

cp's OEIS Frontend

A229889 Number of 8 up, 8 down permutations of [n].

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A229890 Number of 9 up, 9 down permutations of [n].

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Author

Keywords

Examples

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Programs

Maple

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

Views

Author

Keywords

Links

Crossrefs

Programs

Maple