A083411 a(n) = Sum(((k-1)/2)*k!*Stirling_2(n,k),k=1..n).

0, 1, 9, 79, 765, 8311, 100989, 1362439, 20246445, 328972471, 5805917469, 110645911399, 2265191981325, 49589790516631, 1156201277261949, 28605950745797959, 748605590542359405, 20661245832389468791, 599820758571599742429, 18272940402442730318119, 582867486201919540724685

Offset: 1

Author

N. J. A. Sloane, Jun 08 2003

Keywords

• nonn

Crossrefs

Equals A083384(n)/n.

Formula

E.g.f.: (1/2)*( (1-exp(x))/(2-exp(x)) )^2.