A309137 Nonnegative integers of the form 5*x^2 + 5*x*y - y^2.

0, 5, 9, 11, 20, 29, 36, 41, 44, 45, 59, 71, 80, 81, 89, 95, 99, 101, 116, 125, 131, 144, 149, 155, 164, 171, 176, 179, 180, 191, 209, 225, 236, 239, 245, 251, 261, 269, 275, 279, 281, 284, 305, 311, 320, 324, 341, 356, 359, 369, 380, 389, 395, 396, 401, 404

Offset: 1

Author

Hugo Pfoertner, Jul 14 2019

Keywords

• nonn

Comments

Equivalent quadratic form: 9*x^2+15*x*y+5*y^2.

Discriminant of indefinite binary quadratic form: 45.

Nonnegative numbers of the form 5x^2 - 9y^2. - Jon E. Schoenfield, Jun 03 2022

Links

• Will Jagy, C++ program Conway_Positive_All.cc to find all positive numbers represented by an indefinite binary quadratic form
• Peter Luschny, Binary Quadratic Forms
• N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

Crossrefs

Primes in this sequence: A141785.