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A181896
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Least value x solving x^2 - y^2 = n!
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1
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5, 11, 27, 71, 201, 603, 1905, 6318, 21888, 78912, 295260, 1143536, 4574144, 18859680, 80014848, 348776640, 1559776320, 7147792848, 33526120320, 160785625902, 787685472000, 3938427360000, 20082117976800, 104349745817240, 552166953609600, 2973510046027938
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OFFSET
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4,1
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COMMENTS
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Many of terms in this sequence are that same as A055228(n) but not all.
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LINKS
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Table of n, a(n) for n=4..29.
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MATHEMATICA
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cc = {}; Do[f = n!/4; x = Max[Select[Divisors[f], # <= Sqrt[f] &]]; kk = f/x - x; AppendTo[cc, Sqrt[n! + kk^2]], {n, 4, 30}]; cc
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PROG
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(PARI) a(n)=my(N=n!, x=sqrtint(N)); while(!issquare(x++^2-N), ); x \\ Charles R Greathouse IV, Apr 10 2012
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CROSSREFS
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For least y value see A038202.
Cf. A055228.
Sequence in context: A289775 A119503 A048655 * A041671 A215221 A203160
Adjacent sequences: A181893 A181894 A181895 * A181897 A181898 A181899
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KEYWORD
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nonn
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AUTHOR
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Artur Jasinski, Mar 31 2012
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STATUS
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approved
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