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 A197564 #17 Feb 16 2025 08:33:15 %S A197564 1,3,4,18,51,266,1518,11396,111218,1345019,21178437,420441727, %T A197564 10691248879,346431341394,14306876354446,754052504644414 %N A197564 Number of n X n X n 0..6 triangular arrays with each element equal to the number its zero neighbors. %C A197564 Also the number of maximal independent vertex sets (and minimal vertex covers) in the (n-1)-triangular grid graph. - _Eric W. Weisstein_, Jun 14 and Aug 07 2017 %H A197564 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimalVertexCover.html">Minimal Vertex Cover</a> %H A197564 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MaximalIndependentVertexSet.html">Maximal Independent Vertex Set</a> %H A197564 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TriangularGridGraph.html">Triangular Grid Graph</a> %e A197564 Some solutions for 5 X 5 X 5: %e A197564 ......1..........0..........0..........0..........0..........1..........0 %e A197564 .....1.0........2.2........1.2........2.1........1.2........0.2........2.2 %e A197564 ....1.2.2......0.2.0......1.1.0......0.1.1......1.1.0......1.2.0......1.0.1 %e A197564 ...0.2.0.2....2.2.2.2....0.2.2.2....2.2.1.0....0.1.2.2....1.1.1.2....1.2.2.1 %e A197564 ..1.1.1.2.0..0.2.0.2.0..1.2.0.2.0..1.0.1.1.1..1.1.1.0.1..1.0.1.1.0..0.2.0.2.0 %K A197564 nonn %O A197564 1,2 %A A197564 _R. H. Hardin_, Oct 16 2011