A243190 - OEIS

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A243190

Nonnegative numbers of the form -2x^2+6xy+3y^2.

0, 3, 7, 12, 22, 27, 28, 30, 43, 48, 55, 63, 67, 70, 75, 88, 102, 103, 108, 112, 118, 120, 127, 142, 147, 163, 172, 175, 183, 187, 192, 198, 220, 223, 238, 243, 252, 255, 262, 268, 270, 280, 283, 295, 300, 307, 318, 327, 343, 352, 355, 358, 363, 367, 382

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OFFSET

1,2

COMMENTS

Discriminant 60.

Also: nonnegative 3x^2-5y^2 since 3y^2+6xy-2x^2 = 3(y+x)^2-5x^2. - R. J. Mathar, Jun 10 2020

LINKS

Table of n, a(n) for n=1..55.

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

MATHEMATICA

Reap[For[n = 0, n <= 200, n++, If[Reduce[-2*x^2 + 6*x*y + 3*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]

CROSSREFS