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

Offset: 7

Author

Alois P. Heinz, Sep 30 2012

Keywords

• nonn

Comments

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

Examples

			a(7) = 1: 1234567.
a(8) = 7: 12345687, 12345768, 12346578, 12354678, 12435678, 13245678, 21345678.
		

Links

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

Crossrefs

Column k=7 of A047884.

Cf. A007578, A007579, A182172.

Formula

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