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 A307016 #17 Nov 07 2023 14:35:10 %S A307016 0,0,1,1,0,-1,-1,1,2,1,-1,-2,-1,0,2,2,0,-2,-2,1,2,3,3,2,1,-1,-2,-3,-3, %T A307016 -2,-1,0,3,3,0,-3,-3,2,4,2,-2,-4,-2,1,3,4,4,3,1,-1,-3,-4,-4,-3,-1,0,4, %U A307016 4,0,-4,-4,2,3,5,5,3,2,-2,-3,-5,-5,-3,-2,1 %N A307016 List coordinates (x,y) of the points in an hexagonal grid, sorted first by radial coordinate r and in case of ties, by polar angle 0 <= phi < 2*Pi in a polar coordinate system. Sequence gives the second coordinate in a barycentric coordinate system. %C A307016 Cartesian coordinates (x,y) of the grid points are converted to barycentric coordinates (i,j,k) by i = x - y/sqrt(3), j = 2*y/sqrt(3), k = x + y/sqrt(3). The sequence gives j. i is given in A307014, k is given in A307017. %H A307016 Hugo Pfoertner, <a href="/A307016/b307016.txt">Table of n, a(n) for n = 0..9060</a>, covering range r <= 50. %H A307016 Hugo Pfoertner, <a href="/A307014/a307014.gp.txt">PARI program for A307014 and A307016</a>. %o A307016 (PARI) \\ See Link %o A307016 \\ To create the data of this sequence load program from file and call %o A307016 a307014_16(5, 6) \\ Hugo Pfoertner, Nov 07 2023 %Y A307016 Cf. A004016, A035019, A038590, A307014, A307017. %K A307016 sign,look %O A307016 0,9 %A A307016 _Hugo Pfoertner_, Mar 21 2019