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A049263 Smallest nonnegative value taken on by n*x^2 - 4*y^2 for an infinite number of integer pairs (x, y). 0
0, 2, 3, 0, 1, 2, 3, 4, 0, 4, 7, 8, 1, 10, 11, 0, 1, 2, 3, 4, 5, 2, 7, 8, 0, 4, 8, 12, 1, 14, 3, 16, 17, 18, 19, 0, 1, 2, 3, 4, 1, 6, 3, 8, 5, 10, 11, 12, 0, 4, 8, 4, 1, 2, 11, 20, 12, 4, 8, 24, 1, 26, 27, 0, 1, 2, 3, 4, 5, 6, 7, 8, 1, 4, 11, 8, 13, 14, 15, 16, 0, 4, 8, 12, 1, 2, 23, 8, 1, 26, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..91.

MATHEMATICA

p = 4; 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-Fran├žois Alcover, Oct 11 2016 *)

CROSSREFS

Sequence in context: A309954 A124757 A242305 * A014588 A293497 A278164

Adjacent sequences:  A049260 A049261 A049262 * A049264 A049265 A049266

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified August 11 03:41 EDT 2022. Contains 356046 sequences. (Running on oeis4.)