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 A006736 M3597 #19 Oct 04 2019 07:41:01 %S A006736 0,4,24,104,384,1284,4012,11924,34100,94584,255852,677850,1764482, %T A006736 4523924,11447870,28636218,70907326,173991368,423469988,1023162920, %U A006736 2455645268,5858183260,13898041838,32804047708,77067740230 %N A006736 Series for first parallel moment of hexagonal lattice. %C A006736 The hexagonal lattice is the familiar 2-dimensional lattice in which each point has 6 neighbors. This is sometimes called the triangular lattice. %D A006736 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006736 I. Jensen, <a href="/A006736/b006736.txt">Table of n, a(n) for n = 0..90</a> (from link below) %H A006736 J. W. Essam, A. J. Guttmann and K. De'Bell, <a href="https://doi.org/10.1088/0305-4470/21/19/018">On two-dimensional directed percolation</a>, J. Phys. A 21 (1988), 3815-3832. %H A006736 I. Jensen, <a href="https://researchers.ms.unimelb.edu.au/~ij@unimelb/dirperc/series/triabond_t1.ser">More terms</a> %H A006736 Iwan Jensen, Anthony J. Guttmann, <a href="https://arxiv.org/abs/cond-mat/9509121">Series expansions of the percolation probability for directed square and honeycomb lattices</a>, arXiv:cond-mat/9509121, 1995; J. Phys. A 28 (1995), no. 17, 4813-4833. %H A006736 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 A006736 Cf. A006803, A006809, A006737. %K A006736 nonn %O A006736 0,2 %A A006736 _N. J. A. Sloane_, _Simon Plouffe_