A055862 Fourth column of triangle A055858.

0, 0, 0, 36, 400, 5400, 86436, 1605632, 34012224, 810000000, 21435888100, 624333422592, 19851622826256, 684376513673216, 25430282226562500, 1013309916158361600, 43104723599206637824, 1949779138161985486848

Offset: 0

Author

Wolfdieter Lang Jun 20 2000

Keywords

• nonn
• easy

Crossrefs

a(n)=A055858(n, 3). Cf. A000312, A000169, A055860, A055861.

Formula

a(i)=0, i=0, 1, 2; a(n)= (n^2)*(n+1)^(n-2), n >= 3.

E.g.f.: -x*(1+4*x)/2 + (W(-x)^2)*(1-W(-x))/((1+W(-x))*x*2), W(x) principal branch of Lambert's function.