A242661 Nonnegative integers of the form x^2 + 4xy - 2y^2.

0, 1, 3, 4, 9, 10, 12, 16, 19, 25, 27, 30, 36, 40, 43, 46, 48, 49, 57, 58, 64, 67, 73, 75, 76, 81, 90, 94, 97, 100, 106, 108, 115, 120, 121, 129, 138, 139, 142, 144, 145, 147, 160, 163, 169, 171, 172, 174, 184, 190, 192, 193, 196, 201, 202, 211, 219, 225, 228, 232, 235, 241, 243, 250, 256, 265, 268, 270, 282, 283, 289, 291, 292, 298, 300

Offset: 1

Author

N. J. A. Sloane, May 31 2014

Keywords

• nonn

Comments

Discriminant 24.

From Jon E. Schoenfield, Jun 03 2022: (Start)

Also nonnegative integers of the form 3x^2 - 2y^2.

Also nonnegative integers of the form x^2 - 6y^2. (End)

Links

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

Crossrefs

Primes in this sequence = A141170.

Programs

Mathematica

Reap[For[n = 0, n <= 300, n++, If[Reduce[x^2 + 4*x*y - 2*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]