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0, 3, 12, 54, 288, 1800, 12960, 105840, 967680, 9797760, 108864000, 1317254400, 17244057600, 242853811200, 3661488230400, 58845346560000, 1004293914624000, 18140058832896000, 345728180109312000
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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LINKS
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G. C. Greubel, Table of n, a(n) for n = 0..350
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 621
Luis Manuel Rivera, Integer sequences and k-commuting permutations, arXiv preprint arXiv:1406.3081 [math.CO], 2014-2015.
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FORMULA
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E.g.f.: 3*x/(1-x)^2.
Recurrence: a(0)=0, a(1)=3, (n-1)*a(n) = n^2*a(n-1).
a(n) = A122972(n+2) - A122972(n) for n > 0. - Reinhard Zumkeller, Sep 21 2006
For n>0: a(n) = A083746(n+2). - Reinhard Zumkeller, Apr 14 2007
G.f.: 3*Hypergeometric2F0([2,2], [], x). - G. C. Greubel, Jun 12 2022
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MAPLE
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spec := [S, {S=Prod(Sequence(Z), Sequence(Z), Union(Z, Z, Z))}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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Table[3 n n!, {n, 0, 20}] (* Harvey P. Dale, Feb 12 2017 *)
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PROG
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(Magma) [3*(Factorial(n+1)-Factorial(n)): n in [0..30]]; // G. C. Greubel, Jun 12 2022
(SageMath) [3*n*factorial(n) for n in (0..30)] # G. C. Greubel, Jun 12 2022
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CROSSREFS
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Cf. A083746, A122972.
Cf. A000142, A008585.
Sequence in context: A263853 A266083 A245374 * A180589 A042971 A256142
Adjacent sequences: A052670 A052671 A052672 * A052674 A052675 A052676
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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STATUS
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approved
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