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Search: id:A001472
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| A001472 |
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Number of degree-n permutations of order dividing 4.
(Formerly M1292 N0495)
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+0
38
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| 1, 1, 2, 4, 16, 56, 256, 1072, 6224, 33616, 218656, 1326656, 9893632, 70186624, 574017536, 4454046976, 40073925376, 347165733632, 3370414011904, 31426411211776, 328454079574016, 3331595921852416, 37125035407900672, 400800185285464064
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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L. Moser and M. Wyman, On solutions of x^d = 1 in symmetric groups, Canad. J. Math., 7 (1955), 159-168.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.10.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..200
INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 25
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FORMULA
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E.g.f.: exp(x+1/2*x^2+1/4*x^4).
a(0)=1, a(1)=1, a(2)=2, a(3)=4, a(n)=a(n-1)+(n-1)*a(n-2)+(n^3-6n^2+11n-6)*a(n-4) for n>3. [From H. Palsdottir (hronn07(AT)ru.is), Sep 19 2008]
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CROSSREFS
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Cf. A000085, A001470, A053495.
Sequence in context: A104354 A153948 A010362 this_sequence A053498 A005388 A053503
Adjacent sequences: A001469 A001470 A001471 this_sequence A001473 A001474 A001475
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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) and J. H. Conway (conway(AT)math.princeton.edu)
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