A055867 Fourth column of triangle A055864.

0, 0, 0, 64, 750, 10584, 175616, 3359232, 72900000, 1771561000, 47692136448, 1409582685888, 45392319784448, 1582328671875000, 59373627899904000, 2386420683693101056, 102303226385042448384, 4659806991485780193672, 224755712000000000000000, 11444549521935882626568000

Offset

1,4

Links

Table of n, a(n) for n=1..20.

Formula

a(n) = A055864(n, 4).

a(n) = 0 for n = 1, 2, 3; a(n) = n^3*(n+1)^(n-4), n >= 4.

E.g.f.: (9*W(-x)^2 - 14*W(-x)^3 + 3*W(-x)^4 - 9*x^2 - 32*x^3 - 81*x^4)/(72*x), W(x) principal branch of Lambert's function.

a(n) ~ exp(1-9/(2*n)) * n^(n-1). - Amiram Eldar, Feb 07 2026

Maple

A055867:=n->n^3*(n+1)^(n-4): 0, 0, 0, seq(A055867(n), n=4..30); # Wesley Ivan Hurt, Jan 27 2017

Mathematica

a[n_] := If[n < 4, 0, n^3*(n+1)^(n-4)]; Array[a, 20] (* Amiram Eldar, Feb 07 2026 *)

Crossrefs

Cf. A000272, A055864, A055865, A055070, A055866, A055858.

Sequence in context: A108538 A195593 A221753 * A304346 A316217 A305641

Adjacent sequences: A055864 A055865 A055866 * A055868 A055869 A055870

Keyword

nonn,easy

Author

Wolfdieter Lang, Jun 20 2000

Status

approved