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Search: id:A067624
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| A067624 |
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Sqrt((1+cos(y))/2)= sum(n>=0,(-1)^n*y^(2n)/a(n)). |
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4
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| 1, 8, 384, 46080, 10321920, 3715891200, 1961990553600, 1428329123020800, 1371195958099968000, 1678343852714360832000, 2551082656125828464640000, 4714400748520531002654720000, 10409396852733332453861621760000
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=A000165(2n) where A000165(k) are the double factorial numbers 2^k*k!=(2k)!! [Corrected by Johannes W. Meijer (meijgia(AT)hotmail.com), Jul 05 2009]
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), Jul 06 2009: (Start)
a(n) = (4n)!! = 2^(2n)*(2n)!
(End)
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MAPLE
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for n from 0 to 30 by 2 do printf(`%d, `, 2^(n)*(n)!) od:
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CROSSREFS
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Cf. A000165.
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), Jul 06 2009: (Start)
Appears in A162445, A061549 and A120738.
(End)
Sequence in context: A151932 A096205 A162445 this_sequence A096204 A153836 A151941
Adjacent sequences: A067621 A067622 A067623 this_sequence A067625 A067626 A067627
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KEYWORD
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nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Feb 02 2002
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EXTENSIONS
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More terms and Maple code from James A. Sellers (sellersj(AT)math.psu.edu), Feb 11, 2002
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