A226284 [n/2]!*[(n+1)/2]!*C([n/2],3)*C([(n+1)/2],3).

0, 0, 0, 0, 0, 36, 576, 9216, 115200, 1440000, 17280000, 207360000, 2540160000, 31116960000, 398297088000, 5098202726400, 68825736806400, 929147446886400, 13273534955520000, 189621927936000000, 2868031660032000000

Offset

1,6

Comments

Number of permutations of n elements with 6 odd displacements.

Column 4 of A226288.

Column k=6 of A145893, a diagonal of A145894. - Alois P. Heinz, May 29 2014

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Mathematica

Table[Floor[n/2]!Floor[(n+1)/2]!Binomial[Floor[n/2], 3]Binomial[Floor[ (n+1)/2], 3], {n, 30}] (* Harvey P. Dale, Dec 12 2018 *)

Crossrefs

Sequence in context: A183356 A099764 A003841 * A223271 A151597 A263957

Adjacent sequences: A226281 A226282 A226283 * A226285 A226286 A226287

Keyword

nonn

Author

R. H. Hardin, connection of formula with combinatoric problem via N. J. A. Sloane in the Sequence Fans Mailing List, Jun 02 2013

Status

approved