A065088 a(n) = A000166(n)*binomial(n,2).

0, 0, 1, 6, 54, 440, 3975, 38934, 415324, 4805856, 60073245, 807651350, 11630179506, 178681848696, 2918470195459, 50511984152070, 923647710209400, 17795612550034304, 360361154138194809, 7652375096699313126, 170052779926651402990, 3947014523560698353400

Offset

0,4

Links

Table of n, a(n) for n=0..21.

Maple

with (combstruct):with (combinat):a:=proc(m) [ZL, {ZL=Set(Cycle(Z, card>=m))}, labeled]; end: ZLL:=a(2):seq(count(ZLL, size=n)*binomial(n, 2), n=0..21); # Zerinvary Lajos, Jun 11 2008

Mathematica

Table[Subfactorial[n]*Binomial[n, 2], {n, 0, 22}] (* Zerinvary Lajos, Jul 09 2009 *)

Crossrefs

Cf. A000387.

Sequence in context: A043026 A371397 A125837 * A202364 A177484 A353207

Adjacent sequences: A065085 A065086 A065087 * A065089 A065090 A065091

Keyword

nonn

Author

N. J. A. Sloane, Nov 10 2001

Status

approved