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 A243703 #11 Apr 03 2024 10:06:00 %S A243703 0,9,21,31,36,39,41,45,49,51,61,81,84,91,105,119,124,141,144,155,156, %T A243703 159,164,169,180,189,195,196,201,204,205,221,225,244,245,251,255,279, %U A243703 289,291,305,324,329,336,349,351,364,369,371,379,389,401,405,411,419 %N A243703 Nonnegative numbers represented by the indefinite quadratic form -x^2+13xy+9y^2. %C A243703 Discriminant 205. %H A243703 Will Jagy, <a href="/A243655/a243655.txt">C++ program Conway_Positive_All.cc to find all positive numbers represented by an indefinite binary quadratic form</a> %H A243703 Will Jagy, <a href="/A243655/a243655_2.txt">Sample output from Conway_Positive_All.cc</a> %H A243703 N. J. A. Sloane et al., <a href="https://oeis.org/wiki/Binary_Quadratic_Forms_and_OEIS">Binary Quadratic Forms and OEIS</a> (Index to related sequences, programs, references) %o A243703 (C++) // Jagy's program, see link. %o A243703 // Conway_Positive_All -1 13 9 500 %Y A243703 Primes: A243704. %K A243703 nonn %O A243703 1,2 %A A243703 _N. J. A. Sloane_, Jun 17 2014