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%I #25 Oct 31 2016 10:21:39
%S 1,6,13,22,33,37,46,61,69,73,78,94,97,109,118,121,141,142,157,166,169,
%T 177,181,193,213,214,222,229,241,249,253,262,277,286,313,321,334,337,
%U 349,358,366,373,382,393,397,409,421,429,433,438,454,457,478,481
%N Positive numbers that are primitively represented by the indefinite quadratic form x^2 - 3y^2 of discriminant 12.
%C x^2+2xy-2y^2 is an equivalent form.
%H Will Jagy, <a href="/A243655/a243655.txt">C++ program Conway_Positive_All.cc to find all positive numbers represented by an indefinite binary quadratic form</a>
%H Will Jagy, <a href="/A243655/a243655_2.txt">Sample output from Conway_Positive_All.cc</a>
%H Will Jagy, <a href="/A243655/a243655_1.txt">C++ program Conway_Positive_Primitive.cc to find positive numbers primitively represented by an indefinite binary quadratic form</a>
%H Will Jagy, <a href="/A243655/a243655_3.txt">Sample output from Conway_Positive_Prim.cc</a>
%H N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references)
%t Reap[For[n = 1, n < 500, n++, r = Reduce[x^2 - 3 y^2 == n, {x, y}, Integers]; If[r =!= False, If[AnyTrue[{x, y} /. {ToRules[r /. C[1] -> 0]}, CoprimeQ @@ # &], Print[n]; Sow[n]]]]][[2, 1]] (* _Jean-François Alcover_, Oct 31 2016 *)
%Y Cf. A084916 (all numbers represented), A068228.
%K nonn
%O 1,2
%A _N. J. A. Sloane_, Jun 11 2014
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