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Search: id:A051606
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| A051606 |
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(3*n+6)!!!/6!!!, related to A032031 ((3*n)!!! triple factorials). |
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3
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| 1, 9, 108, 1620, 29160, 612360, 14696640, 396809280, 11904278400, 392841187200, 14142282739200, 551549026828800, 23165059126809600, 1042427660706432000, 50036527713908736000, 2551862913409345536000, 137800597324104658944000
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Row m=6 of the array A(4; m,n) := ((3*n+m)(!^3))/m(!^3), m >= 0, n >= 0.
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FORMULA
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a(n) = ((3*n+6)(!^3))/6(!^3); e.g.f.: 1/(1-3*x)^3.
a(n)=n!*3^(n-2)/2, n>=2 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 23 2006
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MAPLE
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[seq(n!*3^(n-2)/2, n=2..18)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 23 2006
with(combstruct):ZL:=[T, {T=Union(Z, Prod(Epsilon, Z, T), Prod(T, Z, Epsilon), Prod(T, Z))}, labeled]:seq(count(ZL, size=i)/6, i=2..18); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Dec 16 2007
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CROSSREFS
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Cf. A032031, A007559(n+1), A034000(n+1), A034001(n+1), A051604-A051609 (rows m=0..9).
Sequence in context: A080505 A104224 A099676 this_sequence A001691 A058421 A128876
Adjacent sequences: A051603 A051604 A051605 this_sequence A051607 A051608 A051609
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KEYWORD
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easy,nonn
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AUTHOR
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Wolfdieter Lang (wolfdieter.lang(AT)physik.uni-karlsruhe.de)
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