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A049261 Smallest nonnegative value taken on by nx^2 - 2y^2 for an infinite number of integer pairs (x, y). 0
1, 0, 1, 2, 2, 4, 5, 0, 1, 2, 1, 4, 2, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 2, 2, 1, 10, 2, 12, 13, 0, 1, 2, 3, 4, 2, 4, 7, 8, 2, 6, 1, 4, 13, 14, 5, 16, 17, 0, 1, 2, 2, 4, 5, 6, 1, 2, 1, 10, 2, 6, 7, 14, 2, 16, 1, 18, 19, 20, 21, 0, 1, 2, 3, 4, 3, 6, 7, 8, 1, 2, 1, 12, 2, 4, 10, 14, 1, 10, 19, 10, 3, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..94.

MATHEMATICA

p = 2; 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, 94}] (* Jean-Fran├žois Alcover, Oct 11 2016 *)

CROSSREFS

Sequence in context: A322253 A059372 A161422 * A135018 A073018 A201509

Adjacent sequences:  A049258 A049259 A049260 * A049262 A049263 A049264

KEYWORD

nonn

AUTHOR

David W. Wilson, Dec 11 1999

STATUS

approved

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Last modified July 2 04:52 EDT 2022. Contains 354985 sequences. (Running on oeis4.)