A201684 a(n) = 2*A052186(n) - n!.

1, -1, 0, 0, 4, 34, 274, 2312, 21034, 207790, 2228892, 25890642, 324477994, 4370180744, 63007469346, 968847653702, 15834053988732, 274170226919434, 5015004366420178, 96645631069563928, 1957433140982004026

Offset

0,5

Links

Vaclav Kotesovec, Table of n, a(n) for n = 0..446

J.-L. Baril, Classical sequences revisited with permutations avoiding dotted pattern, Electronic Journal of Combinatorics, 18 (2011), #P178. See Table 1.

Formula

a(n) ~ n! * (1 - 4/n + 2/n^2 - 2/n^3 - 18/n^4 - 118/n^5 - 948/n^6 - 9120/n^7 - 100728/n^8 - 1250770/n^9 - 17245316/n^10), for coefficients see 2*A256168. - Vaclav Kotesovec, Mar 17 2015

Crossrefs

Cf. A052186, A256168.

Sequence in context: A116430 A216239 A335667 * A155628 A346936 A356286

Adjacent sequences: A201681 A201682 A201683 * A201685 A201686 A201687

Keyword

sign

Author

N. J. A. Sloane, Dec 03 2011

Status

approved