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A243190 Nonnegative numbers of the form -2x^2+6xy+3y^2. 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 (list; graph; refs; listen; history; text; internal format)
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

Primes: A141304. Cf. A243188, A107152, A237606, A141302, A243189, A141303.

Sequence in context: A029452 A294422 A034434 * A256483 A337946 A345433

Adjacent sequences:  A243187 A243188 A243189 * A243191 A243192 A243193

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jun 05 2014

EXTENSIONS

0 prepended and more terms from Colin Barker, Apr 07 2015

STATUS

approved

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Last modified October 25 20:31 EDT 2021. Contains 348256 sequences. (Running on oeis4.)