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Search: id:A007346
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| A007346 |
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Order of group generated by perfect shuffles of 2n cards.
(Formerly M1909)
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+0
1
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| 2, 8, 24, 24, 1920, 7680, 322560, 64, 92897280, 3715891200, 40874803200, 194641920, 25505877196800, 1428329123020800, 21424936845312000, 160, 23310331287699456000, 1678343852714360832000, 31888533201572855808000
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
P. Diaconis, R. L. Graham and W. M. Kantor, The mathematics of perfect shuffles, Adv. Appl. Math., 4 (1983), 175-196.
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LINKS
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Index entries for sequences related to groups
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PROGRAM
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(PARI) A007346(n) = local(M); M=2^n*n!; if(n%4==2, if(n==2, 8, if(n==6, M/6, M)), if(n%4==1, if(n==1, 2, M/2), if(n%4==3, M/2, if(n==2^valuation(n, 2), 2*n*(valuation(n, 2)+1), if(n==12, M/(7!*2), M/4))))) - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Nov 30 2006
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CROSSREFS
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Sequence in context: A018042 A072842 A138387 this_sequence A062247 A084744 A122547
Adjacent sequences: A007343 A007344 A007345 this_sequence A007347 A007348 A007349
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KEYWORD
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nonn,nice,easy
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
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EXTENSIONS
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Corrected and extended by Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Nov 30 2006
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