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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
OFFSET
0,3
LINKS
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
KEYWORD
nonn
AUTHOR
Detlef Pauly (dettodet(AT)yahoo.de), Mar 14 2003
STATUS
approved