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 A049264 Smallest nonnegative value taken on by n*x^2 - 5*y^2 for an infinite number of integer pairs (x, y). 0
 1, 2, 3, 4, 0, 1, 2, 3, 1, 5, 6, 3, 5, 1, 10, 11, 3, 13, 14, 0, 1, 2, 2, 4, 5, 5, 7, 7, 5, 10, 11, 3, 7, 5, 15, 4, 5, 2, 19, 20, 9, 22, 23, 24, 0, 1, 2, 3, 1, 5, 6, 7, 3, 1, 10, 4, 3, 5, 6, 15, 16, 3, 7, 11, 5, 19, 22, 3, 1, 25, 11, 27, 5, 5, 30, 31, 7, 33, 34, 0, 1, 2, 3, 4, 5, 1, 7, 8, 5, 10, 11 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS MATHEMATICA p = 5; f[n_, z_] := FindInstance[x > 0 && y > 0 && n*x^2 - p*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, True, z = z + GCD[n, p], fz = TimeConstrained[f[n, z], 300]; fz = If[fz === \$Aborted, {{x -> Null, y -> Null}}, fz]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x, y} = ", {x, y} /. fz[[1]]]; Return[z]]]; Table[a[n], {n, 1, 91}] (* Jean-François Alcover, Oct 11 2016 *) CROSSREFS Sequence in context: A197024 A031235 A090141 * A010874 A278182 A125926 Adjacent sequences:  A049261 A049262 A049263 * A049265 A049266 A049267 KEYWORD nonn AUTHOR STATUS approved

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Last modified December 15 01:20 EST 2018. Contains 318141 sequences. (Running on oeis4.)