A052140 4^n*n!^2*Sum_{k=0..n} 1/k!.

1, 8, 160, 6144, 399360, 40058880, 5771427840, 1131282432000, 289610945003520, 93834041307955200, 37533620328254668800, 18166272406298453606400, 10463772914064222584832000, 7073510490325302759338803200, 5545632224438439107673194496000

Offset

0,2

References

R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Problem 5.64(d).

Links

Table of n, a(n) for n=0..14.

Crossrefs

Sequence in context: A036909 A369539 A221077 * A219265 A300466 A184605

Adjacent sequences: A052137 A052138 A052139 * A052141 A052142 A052143

Keyword

nonn

Author

N. J. A. Sloane, Jan 23 2000

Status

approved