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A007346 Order of group generated by perfect shuffles of 2n cards.
(Formerly M1909)
+0
1
2, 8, 24, 24, 1920, 7680, 322560, 64, 92897280, 3715891200, 40874803200, 194641920, 25505877196800, 1428329123020800, 21424936845312000, 160, 23310331287699456000, 1678343852714360832000, 31888533201572855808000 (list; graph; listen)
OFFSET

1,1

REFERENCES

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.

LINKS

Index entries for sequences related to groups

PROGRAM

(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

CROSSREFS

Sequence in context: A018042 A072842 A138387 this_sequence A062247 A084744 A122547

Adjacent sequences: A007343 A007344 A007345 this_sequence A007347 A007348 A007349

KEYWORD

nonn,nice,easy

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)

EXTENSIONS

Corrected and extended by Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Nov 30 2006

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Last modified December 18 21:37 EST 2009. Contains 171024 sequences.


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