A243174 Nonnegative integers of the form x^2 + 5*x*y - 5*y^2 (discriminant 45).

0, 1, 4, 9, 16, 19, 25, 31, 36, 45, 49, 55, 61, 64, 76, 79, 81, 99, 100, 109, 121, 124, 139, 144, 145, 151, 169, 171, 180, 181, 196, 199, 205, 211, 220, 225, 229, 241, 244, 256, 261, 271, 279, 289, 295, 304, 316, 319, 324, 331, 349, 355, 361, 369, 379, 396, 400, 405, 409, 421, 436, 439, 441, 445, 451, 475, 484, 495, 496, 499, 505, 529, 531, 541, 549

Offset

1,3

Comments

Also numbers representable as x^2 + 7*x*y + y^2 with 0 <= x <= y. - Gheorghe Coserea, Jul 29 2018

Also numbers of the form x^2 - x*y - 11*y^2 with 0 <= x <= y (or x^2 + x*y - 11*y^2 with x, y nonnegative). - Jianing Song, Jul 31 2018

Also nonnegative integers of the form 9x^2 - 5y^2. - Jon E. Schoenfield, Jun 03 2022

Links

Gheorghe Coserea, Table of n, a(n) for n = 1..100001

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

Crossrefs

Cf. A028957, A031363.

Primes: A033212.

Sequence in context: A035234 A313325 A313326 * A313327 A313328 A313329

Adjacent sequences: A243171 A243172 A243173 * A243175 A243176 A243177

Keyword

nonn

Author

N. J. A. Sloane, Jun 01 2014

Status

approved