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 A049247 Smallest nonnegative value taken on by 8x^2 - ny^2 for an infinite number of integer pairs (x, y). 0
 4, 0, 5, 4, 3, 2, 1, 0, 8, 8, 8, 8, 8, 2, 8, 8, 4, 0, 8, 8, 8, 2, 1, 8, 7, 6, 5, 4, 3, 2, 1, 0, 8, 8, 8, 8, 8, 2, 8, 8, 8, 8, 5, 8, 8, 2, 1, 8, 4, 0, 8, 8, 3, 2, 8, 8, 8, 8, 8, 8, 8, 2, 8, 8, 7, 6, 5, 4, 3, 2, 1, 0, 8, 8, 8, 8, 8, 8, 1, 8, 8, 8, 5, 8, 8, 2, 8, 8, 8, 8, 8, 4, 8, 2, 8, 8, 4, 0, 8, 8, 3, 2, 1, 8, 8 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Table of n, a(n) for n=1..105. MATHEMATICA p = 8; f[n_, z_] := FindInstance[x > 0 && y > 0 && p*x^2 - n*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, z <= p, z = z + GCD[n, p], Which[n == 49, z = 4; fz = \$Aborted, n == 81, z = 8; fz = \$Aborted, n == 83, z = 5; fz = \$Aborted, n == 101, z = 3; fz = \$Aborted, True, 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, 105}] (* Jean-François Alcover, Oct 11 2016 *) CROSSREFS Sequence in context: A201196 A019906 A197251 * A175621 A016578 A268631 Adjacent sequences: A049244 A049245 A049246 * A049248 A049249 A049250 KEYWORD nonn AUTHOR David W. Wilson STATUS approved

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Last modified August 8 18:48 EDT 2024. Contains 375023 sequences. (Running on oeis4.)