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 A027740 #32 Jul 18 2025 09:33:47 %S A027740 1,2,4,14,60,384,3318,40638,689636,16383974,542420394,25075022590, %T A027740 1617185558560,145563089994148,18283036276489970,3204638749437865046, %U A027740 783848125594781710150,267554112823378352976752 %N A027740 Number of independent subsets of nodes in graph formed from n-fold subdivision of triangle. %C A027740 In other words, number of independent vertex sets (and vertex covers) in the (n-1)-triangular grid graph. - _Eric W. Weisstein_, Jun 14 2017 %C A027740 Number of planar n X n X n binary triangular grids with no more than 1 one in any similarly oriented 2 X 2 X 2 subtriangle. - _R. H. Hardin_, Dec 27 2008 %H A027740 Liang Kai, <a href="/A027740/b027740.txt">Table of n, a(n) for n = 0..40</a> %H A027740 Kai Liang, <a href="https://arxiv.org/abs/2507.04007">Independent Set Enumeration and Estimation of Related Constants of Grid Graphs</a>, arXiv:2507.04007 [math.CO], 2025. See pp. 1, 10. %H A027740 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/IndependentVertexSet.html">Independent Vertex Set</a> %H A027740 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularGridGraph.html">Triangular Grid Graph</a> %H A027740 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/VertexCover.html">Vertex Cover</a> %Y A027740 Cf. A239567, A239438, A287064. %K A027740 nonn,nice %O A027740 0,2 %A A027740 _R. H. Hardin_