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 A309137 #8 Jun 03 2022 18:09:23 %S A309137 0,5,9,11,20,29,36,41,44,45,59,71,80,81,89,95,99,101,116,125,131,144, %T A309137 149,155,164,171,176,179,180,191,209,225,236,239,245,251,261,269,275, %U A309137 279,281,284,305,311,320,324,341,356,359,369,380,389,395,396,401,404 %N A309137 Nonnegative integers of the form 5*x^2 + 5*x*y - y^2. %C A309137 Equivalent quadratic form: 9*x^2+15*x*y+5*y^2. %C A309137 Discriminant of indefinite binary quadratic form: 45. %C A309137 Nonnegative numbers of the form 5x^2 - 9y^2. - _Jon E. Schoenfield_, Jun 03 2022 %H A309137 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 A309137 Peter Luschny, <a href="https://oeis.org/wiki/User:Peter_Luschny/BinaryQuadraticForms#Implementation">Binary Quadratic Forms</a> %H A309137 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 A309137 (C++) See Jagy link. %Y A309137 Primes in this sequence: A141785. %K A309137 nonn %O A309137 1,2 %A A309137 _Hugo Pfoertner_, Jul 14 2019