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Search: id:A095986
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| A095986 |
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A card-arranging problem: number of permutations p_1, ..., p_n of 1, ..., n such that i + p_i is a square for every i. |
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+0
5
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| 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 2, 4, 3, 2, 5, 15, 21, 66, 37, 51, 144, 263, 601, 1333, 2119, 2154, 2189, 3280, 12405, 55329, 160895, 588081, 849906, 1258119, 1233262, 2478647, 4305500, 17278636, 47424179, 153686631, 396952852, 1043844982
(list; graph; listen)
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OFFSET
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1,14
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COMMENT
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Gardner attributes the problem (for the case n = 13) to David L. Silverman.
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REFERENCES
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M. Gardner, Mathematical Games column, Scientific American, Nov 1974.
M. Gardner, Mathematical Games column, Scientific American, Mar 1975.
M. Gardner, Time Travel and Other Mathematical Bewilderments. Freeman, NY, 1988, p. 81.
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CROSSREFS
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Cf. A006063 (for cubes).
Sequence in context: A049848 A060806 A128868 this_sequence A059908 A084936 A099066
Adjacent sequences: A095983 A095984 A095985 this_sequence A095987 A095988 A095989
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KEYWORD
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nonn
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AUTHOR
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Frank Adams-Watters (FrankTAW(AT)Netscape.net), Jul 18 2004
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EXTENSIONS
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a(32) and a(33) from John W. Layman (layman(AT)math.vt.edu), Jul 21 2004
a(34)-a(36) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jul 26 2004
More terms from William Rex Marshall (w.r.marshall(AT)actrix.co.nz), Apr 18 2006
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