A165793 a(0)=1, a(n)=n*(a(n-1)-2).

1, -1, -6, -24, -104, -530, -3192, -22358, -178880, -1609938, -16099400, -177093422, -2125121088, -27626574170, -386772038408, -5801580576150, -92825289218432, -1578029916713378, -28404538500840840

Offset: 0

Author

Philippe Deléham, Sep 26 2009

Keywords

• sign

Links

• G. C. Greubel, Table of n, a(n) for n = 0..250

Programs

Mathematica

RecurrenceTable[{a[0]==1,a[n]==n*(a[n-1]-2)},a[n],{n,30}] (* Harvey P. Dale, Jul 19 2011 *)
FoldList[#1*#2 - 2 #2 &, 1, Range[25]] (* G. C. Greubel, Apr 08 2016 *)

Formula

a(n) = n! - 2*floor(e*n!)+2 , n>0. - Gary Detlefs, Jun 19 2010

Extensions

Corrected by Harvey P. Dale, Jul 19 2011