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A034910
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One quarter of octo-factorial numbers.
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4
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1, 12, 240, 6720, 241920, 10644480, 553512960, 33210777600, 2258332876800, 171633298636800, 14417197085491200, 1326382131865190400, 132638213186519040000, 14324927024144056320000
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OFFSET
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1,2
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COMMENTS
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A034910 occurs in connection with the Vandermonde permanent of (1,3,5,7,9,...); see the Mathematica section of A203516. [From Clark Kimberling, Jan 03 2012]
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LINKS
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Table of n, a(n) for n=1..14.
Index entries for sequences related to factorial numbers
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FORMULA
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4*a(n) = (8*n-4)(!^8) := product(8*j-4, j=1..n) = 4^n*A001147(n) = 2^n*(2*n)!/n!, A001147(n) := (2*n-1)!!; E.g.f. (-1+(1-8*x)^(-1/2))/4.
a(n) = A090802(2n-1, n). - Ross La Haye (rlahaye(AT)new.rr.com), Oct 18 2005
a(n)=(2*n)!/(n)!*2^(n-2). - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 25 2006
G.f.: x/(1-12x/(1-8x/(1-20x/(1-16x/(1-28x/(1-24x/(1-36x/(1-32x/(1-... (continued fraction). - Philippe Deléham, Jan 07 2011
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MAPLE
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[seq((2*n)!/(n)!*2^(n-2), n=1..14)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Sep 25 2006
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MATHEMATICA
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s=1; lst={s}; Do[s+=n*s; AppendTo[lst, s], {n, 11, 5!, 8}]; lst [From Vladimir Joseph Stephan Orlovsky, Nov 08 2008]
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CROSSREFS
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Cf. A001147, A045755, A034908-A034912, A203516.
Sequence in context: A009150 A009080 A002166 * A091745 A012344 A012542
Adjacent sequences: A034907 A034908 A034909 * A034911 A034912 A034913
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KEYWORD
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easy,nonn
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AUTHOR
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Wolfdieter Lang
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STATUS
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approved
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