This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A372518 #7 May 04 2024 10:30:05
%S A372518 1,5,21,39,51,59,81,91,105,119,131,139,141,159,189,195,201,221,241,
%T A372518 255,269,271,279,291,295,329,351,359,369,371,405,409,411,441,455,459,
%U A372518 469,471,501,541,549,569,579,595,599,611,651,655,661,679,681,689,695,699
%N A372518 Positive numbers primitively represented by the indefinite quadratic form x^2 + 13xy - 9y^2.
%C A372518 Discriminant 205.
%H A372518 Peter Luschny, <a href="https://github.com/PeterLuschny/BinaryQuadraticForms">Binary Quadratic Forms</a>, GitHub 2024.
%o A372518 (SageMath)
%o A372518 load('https://raw.githubusercontent.com/PeterLuschny/BinaryQuadraticForms/main/BinaryQF.sage')
%o A372518 Q = binaryQF([1, 13, -9])
%o A372518 print(Q.represented_positives(700, 'primitively'))
%Y A372518 Cf. A243701 (primes), A243702 (all), this sequence (primitively).
%K A372518 nonn
%O A372518 1,2
%A A372518 _Peter Luschny_, May 04 2024