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 A028929 #15 Jul 08 2025 18:56:45 %S A028929 0,2,3,4,6,8,9,12,13,16,18,24,26,27,29,31,32,36,39,41,46,47,48,50,52, %T A028929 54,58,62,64,69,71,72,73,75,78,81,82,87,92,93,94,96,98,100,104,108, %U A028929 116,117,118,123,124,127,128,131,138,139,141,142,144,146,147,150,151,156 %N A028929 Numbers represented by quadratic form with Gram matrix [ 4, 1; 1, 6 ], divided by 2. %C A028929 Nonnegative integers of the form 2x^2 + x*y + 3y^2, a positive definite quadratic form of discriminant -23. - _N. J. A. Sloane_, Jul 09 2014 %H A028929 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) %Y A028929 For primes see A106867. Cf. A028958, A033217. %K A028929 nonn,easy %O A028929 1,2 %A A028929 _N. J. A. Sloane_ %E A028929 Corrected and extended by Larry Reeves (larryr(AT)acm.org), Mar 29 2000