A052570 E.g.f.: x/(1-4*x).

0, 1, 8, 96, 1536, 30720, 737280, 20643840, 660602880, 23781703680, 951268147200, 41855798476800, 2009078326886400, 104472072998092800, 5850436087893196800, 351026165273591808000, 22465674577509875712000

Offset: 0

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Keywords

• easy
• nonn

Links

• INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 513

Crossrefs

A034177 is an essentially identical sequence. - Philippe Deléham, Sep 18 2008

Programs

Maple

spec := [S,{S=Prod(Z,Sequence(Union(Z,Z,Z,Z)))},labeled]: seq(combstruct[count](spec,size=n), n=0..20);

Mathematica

With[{nn=20},CoefficientList[Series[x/(1-4x),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Jan 15 2017 *)

Formula

Recurrence: {a(1)=1, a(0)=0, (-4-4*n)*a(n)+a(n+1)=0.}

4^(n-1)*n!=n!*A000302(n-1). for n >= 1.