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A076301 Related to number of labeled partially ordered sets. 1
1, 1, 3, 15, 96, 720, 6120, 57960, 604800, 6894720, 85276800, 1137628800, 16286054400, 249080832000, 4053790540800, 69960578688000, 1276290183168000, 24542432538624000, 496183962193920000, 10522301185363968000 (list; graph; refs; listen; history; text; internal format)
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: A220262 A306027 A304072 * A112913 A109283 A079689

Adjacent sequences:  A076298 A076299 A076300 * A076302 A076303 A076304

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified November 23 16:18 EST 2020. Contains 338590 sequences. (Running on oeis4.)