A217327 - OEIS

A217327

Number of self-inverse permutations in S_n with longest increasing subsequence of length 7.

1, 7, 55, 319, 1904, 10275, 56135, 294386, 1556323, 8086433, 42298721, 219795160, 1149139210, 5999688692, 31506046052, 165664633982, 875886376212, 4643488263933, 24746018418741, 132328997879066, 711142850556217, 3836134976520394, 20791024498584110

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OFFSET

7,2

COMMENTS

Also the number of Young tableaux with n cells and 7 rows.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 7..400

FORMULA

a(n) = A182172(n,7)-A182172(n,6) = A007578(n)-A007579(n).

EXAMPLE

a(7) = 1: 1234567.

a(8) = 7: 12345687, 12345768, 12346578, 12354678, 12435678, 13245678, 21345678.

CROSSREFS

Column k=7 of A047884.

Cf. A007578, A007579, A182172.

Sequence in context: A272864 A121183 A291891 * A069404 A198689 A320091

Adjacent sequences: A217324 A217325 A217326 * A217328 A217329 A217330

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Sep 30 2012

STATUS

approved