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 A038591 #8 Jul 08 2025 22:25:03 %S A038591 1,3,6,7,12,13,18,19,21,27,30,31,36,37,42,43,48,54,55,61,63,69,73,75, %T A038591 78,84,85,90,91,96,97,102,109,114,120,121,123,127,129,135,139,141,144, %U A038591 150,151,156,163,168,169,174,180 %N A038591 Sizes of clusters in hexagonal lattice A_2 with 3-fold symmetry. %C A038591 The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice. %H A038591 G. Nebe and N. J. A. Sloane, <a href="http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/A2.html">Home page for hexagonal (or triangular) lattice A2</a> %Y A038591 Union of A038588 and A038590. %K A038591 nonn %O A038591 0,2 %A A038591 _N. J. A. Sloane_