A242664 Nonnegative integers of the form x^2 + 6xy - y^2.

0, 1, 4, 6, 9, 10, 15, 16, 24, 25, 26, 31, 36, 39, 40, 41, 49, 54, 60, 64, 65, 71, 74, 79, 81, 86, 89, 90, 96, 100, 104, 106, 111, 121, 124, 129, 134, 135, 144, 150, 151, 156, 159, 160, 164, 166, 169, 185, 186, 191, 196, 199, 201, 214, 215, 216, 225, 234, 239, 240, 241, 246, 249, 250, 256, 260, 265, 271, 279, 281, 284, 289, 294, 296

Offset: 1

Author

N. J. A. Sloane, May 31 2014

Keywords

• nonn

Comments

Discriminant 40.

Nonnegative integers of the form x^2 - 10y^2. - Jon E. Schoenfield, Jun 03 2022

Links

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

Crossrefs

Primes in this sequence = A141180.

Programs

Mathematica

Reap[For[n = 0, n <= 300, n++, If[Reduce[ x^2 + 6*x*y - 1*y^2 == n, {x, y}, Integers] =!= False, Sow[n]]]][[2, 1]]
Select[Range[0, 300], Reduce[x^2 + 6 x y - y^2 == #, {x, y}, Integers] =!= False &] (* Ed Pegg Jr, Jun 26 2025 *)