A372518 Positive numbers primitively represented by the indefinite quadratic form x^2 + 13xy - 9y^2.

1, 5, 21, 39, 51, 59, 81, 91, 105, 119, 131, 139, 141, 159, 189, 195, 201, 221, 241, 255, 269, 271, 279, 291, 295, 329, 351, 359, 369, 371, 405, 409, 411, 441, 455, 459, 469, 471, 501, 541, 549, 569, 579, 595, 599, 611, 651, 655, 661, 679, 681, 689, 695, 699

Offset: 1

Author

Peter Luschny, May 04 2024

Keywords

• nonn

Comments

Discriminant 205.

Links

• Peter Luschny, Binary Quadratic Forms, GitHub 2024.

Crossrefs

Cf. A243701 (primes), A243702 (all), this sequence (primitively).

Programs

SageMath

load('https://raw.githubusercontent.com/PeterLuschny/BinaryQuadraticForms/main/BinaryQF.sage')
Q = binaryQF([1, 13, -9])
print(Q.represented_positives(700, 'primitively'))