A320255 a(n) = n! * [x^n] log(1 + exp(x)*(x + (n/2 - 1)*x^2)).

0, 1, 1, -1, -26, 39, 3666, -7400, -1488416, 3802113, 1322570530, -4095154284, -2187371499312, 7964242253473, 6052757424558586, -25343867475914910, -25988018018090461664, 123032891453320498449, 163684285184147641156098, -864557405968781387651984, -1448111703094244548802632160

Offset

0,5

Comments

For n > 2, a(n) is the n-th term of the logarithmic transform of n-gonal numbers.

Links

Table of n, a(n) for n=0..20.

N. J. A. Sloane, Transforms

Index to sequences related to polygonal numbers

Mathematica

Table[n! SeriesCoefficient[Log[1 + Exp[x] (x + (n/2 - 1) x^2)], {x, 0, n}], {n, 0, 20}]

Crossrefs

Cf. A009306, A033464, A300455, A318118, A318124, A320254.

Sequence in context: A105997 A354345 A075288 * A348286 A125218 A174990

Adjacent sequences: A320252 A320253 A320254 * A320256 A320257 A320258

Keyword

sign

Author

Ilya Gutkovskiy, Oct 08 2018

Status

approved