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Search: id:A034000
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| A034000 |
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One half of triple factorial numbers. |
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+0
20
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| 1, 5, 40, 440, 6160, 104720, 2094400, 48171200, 1252451200, 36321084800, 1162274713600, 40679614976000, 1545825369088000, 63378840132608000, 2788668965834752000, 131067441394233344000, 6553372069711667200000
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OFFSET
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1,2
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FORMULA
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2*a(n+1) = (3*n+2)!!! := product(3*j+2, j=0..n), n >= 0; E.g.f. (-1+(1-3*x)^(-2/3))/2; a(n) = (3*n-1)!/(2*3^(n-1)*(n-1)!*A007559(n)).
a(n) ~ 3/2*2^(1/2)*pi^(1/2)*Gamma(2/3)^-1*n^(7/6)*3^n*e^-n*n^n*{1 + 23/36*n^-1 + ...}. - Joe Keane (jgk(AT)jgk.org), Nov 23 2001
a(n)=3^(n)*(n+2/3)!/(2/3)! - Paul Barry (pbarry(AT)wit.ie), Sep 04 2005
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CROSSREFS
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Cf. A007559, A034001, A025748, A034724.
Sequence in context: A061633 A143437 A083304 this_sequence A000359 A121886 A052868
Adjacent sequences: A033997 A033998 A033999 this_sequence A034001 A034002 A034003
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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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