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 A181896 Least value x solving x^2 - y^2 = n! 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 4,1 COMMENTS Many of terms in this sequence are that same as A055228(n) but not all. LINKS MATHEMATICA 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 PROG (PARI) a(n)=my(N=n!, x=sqrtint(N)); while(!issquare(x++^2-N), ); x \\ Charles R Greathouse IV, Apr 10 2012 CROSSREFS 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 KEYWORD nonn AUTHOR Artur Jasinski, Mar 31 2012 STATUS approved

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Last modified October 19 14:36 EDT 2019. Contains 328222 sequences. (Running on oeis4.)