A136592 Column 2 of triangle A136590.

1, 3, -13, -10, 394, -2016, -5076, 170064, -1155024, -5005440, 193724640, -1656720000, -10280355840, 465087087360, -4804977542400, -39012996556800, 2035558551398400, -24660231399014400, -248246498826547200, 14713557956794368000

Offset: 2

Author

Paul D. Hanna, Jan 10 2008

Keywords

• sign

Examples

			E.g.f.: A(x) = 1*x^2/2! + 3*x^3/3! - 13*x^4/4! - 10*x^5/5! + 394*x^6/6! +...
		

Crossrefs

Cf. A136590, A136591, A136593, A136594.

Programs

Mathematica

With[{nn=30},Drop[CoefficientList[Series[Log[1+x+x^2]^2/2,{x,0,nn}],x] Range[ 0,nn]!,2]] (* Harvey P. Dale, Feb 28 2013 *)

PARI

a(n)=(n+2)!*polcoeff(log(1+x+x^2 +x*O(x^(n+2)))^2/2!,n+2)

Formula

E.g.f.: A(x) = log(1 + x + x^2)^2 / 2!.