A076301 Related to number of labeled partially ordered sets.

1, 1, 3, 15, 96, 720, 6120, 57960, 604800, 6894720, 85276800, 1137628800, 16286054400, 249080832000, 4053790540800, 69960578688000, 1276290183168000, 24542432538624000, 496183962193920000, 10522301185363968000

Offset

0,3

Links

G. C. Greubel, Table of n, a(n) for n = 0..445

M. Janjic and B. Petkovic, A Counting Function, arXiv 1301.4550 [math.CO], 2013

Formula

E.g.f.: -(2-4*x + 3*x^2)/(-6*x^2 - 2 + 6*x + 2*x^3).

a(n) = (4 - n + n^2)*n!/4. - G. C. Greubel, May 04 2018

Maple

seq(1/4*(4-n+n^2)*n!, n=0..30);

Mathematica

Table[(4 -n +n^2)*n!/4, {n, 0, 30}] (* G. C. Greubel, May 04 2018 *)

Prog

(PARI) for(n=0, 30, print1((4 -n +n^2)*n!/4, ", ")) \\ G. C. Greubel, May 04 2018
(Magma) [(4 -n +n^2)*Factorial(n)/4: n in [0..30]]; // G. C. Greubel, May 04 2018

Crossrefs

Sequence in context: A306027 A354412 A304072 * A112913 A109283 A370210

Adjacent sequences: A076298 A076299 A076300 * A076302 A076303 A076304

Keyword

nonn

Author

Detlef Pauly (dettodet(AT)yahoo.de), Mar 14 2003

Status

approved