%I #8 Oct 09 2016 05:34:10
%S 1,2,1,1,1,6,7,8,9,10,0,1,2,3,1,4,6,7,8,4,10,11,1,13,1,5,1,13,2,19,1,
%T 13,22,5,19,9,1,3,7,29,6,31,32,0,1,2,1,4,5,6,7,8,1,10,11,5,13,14,1,1,
%U 2,2,7,5,6,22,1,17,1,5,1,13,13,7,1,13,33,34,7,16,25,22,8,13,10,3,19,44,1
%N Smallest nonnegative value taken on by nx^2 - 11y^2 for an infinite number of integer pairs (x, y).
%t f[n_, z_] := FindInstance[x > 0 && y > 0 && n*x^2 - 11*y^2 == z, {x, y}, Integers, 1]; a[n_] := For[z = 0, True, z = z + GCD[n, 11], fz = f[n, z]; If[fz =!= {}, Print["a(", n, ") = ", z, " {x,y} = ", {x, y} /. fz[[1]]]; Return[z]]]; Array[a, 89] (* _Jean-François Alcover_, Oct 09 2016 *)
%K nonn
%O 1,2
%A _David W. Wilson_