A243185 Nonnegative numbers of the form -2*x^2+3*x*y+3*y^2.

0, 1, 3, 4, 9, 12, 16, 22, 25, 27, 31, 34, 36, 37, 48, 49, 58, 64, 66, 67, 75, 81, 82, 88, 93, 97, 100, 102, 103, 108, 111, 121, 124, 136, 144, 147, 148, 157, 163, 166, 169, 174, 181, 187, 192, 196, 198, 199, 201, 202, 214, 223, 225, 229, 232, 243, 246, 256, 262, 264, 268, 279, 289, 291, 298, 300

Offset

1,3

Comments

Discriminant 33.

I do not understand why the Mathematica program misses out 0.

Links

Table of n, a(n) for n=1..66.

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

Mathematica

Reap[For[n = 0, n <= 300, n++, If[Reduce[-2*x^2 + 3*x*y + 3*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]

Crossrefs

For primes see A141177.

Sequence in context: A112169 A155564 A105137 * A336166 A230781 A025613

Adjacent sequences: A243182 A243183 A243184 * A243186 A243187 A243188

Keyword

nonn

Author

N. J. A. Sloane, Jun 04 2014

Status

approved