A055865 Second column of triangle A055864.

0, 2, 12, 100, 1080, 14406, 229376, 4251528, 90000000, 2143588810, 56757583872, 1654301902188, 52644347205632, 1816448730468750, 67553994410557440, 2694045224950414864, 114692890480116793344, 5191945444217181018258

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

Formula

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

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

a(n)=A055864(n, 2).

Crossrefs

Cf. A055864, A000272, A055858.

Sequence in context: A303614 A124102 A168365 * A085389 A202013 A151505

Adjacent sequences: A055862 A055863 A055864 * A055866 A055867 A055868

Keyword

nonn,easy

Author

Wolfdieter Lang Jun 20 2000

Status

approved