A154655 Number of permutations of length n within distance 6.

1, 1, 2, 6, 24, 120, 720, 5040, 30960, 172200, 899064, 4553166, 22934774, 116914351, 610093513, 3222826972, 17101449940, 90706002192, 479654768640, 2527274267136, 13280313508416, 69734129749632, 366283822765632, 1925290900630896, 10126754515065868

Offset: 0

Author

Torleiv Kløve, Jan 13 2009

Keywords

• nonn
• easy

Comments

a(n) equals the permanent of the n X n matrix with 1's along the central thirteen diagonals, and 0's everywhere else. - John M. Campbell, Jul 10 2011

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1000 (terms n=1..400 from R. H. Hardin)
• Torleiv Kløve, Spheres of Permutations under the Infinity Norm - Permutations with limited displacement, Reports in Informatics, Department of Informatics, University of Bergen, Norway, no. 376, November 2008.

Crossrefs

Cf. A000045, A002524, A002526, A072856, A154654.

Column k=6 of A306209.

Formula

G.f. is a rational function f(x)/g(x) where f has degree 482 and g has degree 494.

Extensions

a(0)=1 prepended by Alois P. Heinz, Jan 28 2019