A178453 Numerator of n!*Sum((-1)^k/k!, k=0..n)/(n-1)^n.

1, 1, 1, 11, 53, 103, 2119, 16687, 16481, 1468457, 1456321, 63633137, 2467007773, 34361893981, 171045872261, 8178130767479, 138547156531409, 92079694567171, 47106033220679059, 939765362752547227, 6563440628747948887, 39299278806015611311, 9923922230666898717143, 79253545592131482810517, 5934505493938805432851513, 154068892631103602583645049, 461572649528573755888451011, 116167945043852116348068366947, 3364864615063302680426807870189

Offset

2,4

Comments

The fraction is a lower bound on certain permanents.

References

G. P. Egorychev, Van der Waerden conjecture and applications, pp. 3-26 in Handbook of Algebra, Vol. 1, ed. M. Hazewinkel, Elsevier, 1996.

Links

Table of n, a(n) for n=2..30.

Example

1, 1/4, 1/9, 11/256, 53/3125, 103/15552, 2119/823543, 16687/16777216, 16481/43046721, ...

Crossrefs

See A178454 for denominators.

Sequence in context: A004622 A045471 A086715 * A225582 A164580 A141893

Adjacent sequences: A178450 A178451 A178452 * A178454 A178455 A178456

Keyword

nonn,frac

Author

N. J. A. Sloane, Dec 22 2010

Status

approved