A049269 - OEIS

%I #8 Oct 09 2016 05:33:58

%S 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,

%T 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,

%U 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

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

%t 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 *)

%K nonn

%O 1,2

%A _David W. Wilson_