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A243702
Nonnegative numbers represented by the indefinite quadratic form x^2 + 13xy - 9y^2.
3
0, 1, 4, 5, 9, 16, 20, 21, 25, 36, 39, 45, 49, 51, 59, 64, 80, 81, 84, 91, 100, 105, 119, 121, 125, 131, 139, 141, 144, 156, 159, 169, 180, 189, 195, 196, 201, 204, 221, 225, 236, 241, 245, 255, 256, 269, 271, 279, 289, 291, 295, 320, 324, 329, 336, 351, 359
OFFSET
1,3
COMMENTS
Discriminant 205.
PROG
(C++) // Jagy's program, see link.
// Conway_Positive_All 1 13 -9 500
(SageMath)
load('https://raw.githubusercontent.com/PeterLuschny/BinaryQuadraticForms/main/BinaryQF.sage')
Q = binaryQF([1, 13, -9])
print(Q.represented_positives(360, 'all')) # '0' is missing as indicated by the function name. # Peter Luschny, May 04 2024
CROSSREFS
Cf. A243701 (primes), A243702 (this sequence), A372518 (primitively).
Sequence in context: A087948 A010437 A020682 * A155565 A278336 A051216
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jun 17 2014
STATUS
approved