A049269 Smallest nonnegative value taken on by nx^2 - 10y^2 for an infinite number of integer pairs (x, y).

1, 2, 2, 4, 5, 6, 2, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 2, 1, 10, 11, 12, 2, 6, 10, 10, 2, 2, 10, 20, 6, 22, 15, 6, 25, 26, 3, 28, 29, 0, 1, 2, 2, 4, 5, 4, 2, 8, 1, 10, 6, 10, 10, 14, 5, 14, 17, 10, 1, 20, 6, 22, 2, 6, 10, 14, 2, 10, 6, 30, 31, 8, 10, 10, 35, 4, 22, 38, 6, 40, 26, 18, 2, 44, 45

Offset

1,2

Links

Table of n, a(n) for n=1..85.

Mathematica

f[n_, z_] := FindInstance[x>0 && y>0 && n*x^2 - 10*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, True, z = z + GCD[n, 10], fz = f[n, z]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x, y} = ", {x, y} /. fz[[1]]]; Return[z]]]; Array[a, 85] (* Jean-François Alcover, Oct 09 2016 *)

Crossrefs

Sequence in context: A240851 A261665 A208096 * A085085 A121600 A126870

Adjacent sequences: A049266 A049267 A049268 * A049270 A049271 A049272

Keyword

nonn

Author

David W. Wilson

Status

approved