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 A159867 #18 Feb 16 2025 08:33:10 %S A159867 1,3,12,60,375,2613,19074,143660,1101860,8562292,67206242,531804577, %T A159867 4236708679 %N A159867 Number of 2-sided n-triangular polyedges. %H A159867 R. J. Mathar, <a href="/A159867/a159867.pdf">OEIS A159867</a> %H A159867 Ed Pegg, Jr., <a href="http://demonstrations.wolfram.com/PolyformExplorer/">Illustrations of polyforms</a> %H A159867 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyedge.html">Polyedge</a> %Y A159867 Cf. A151539, A151540, A151541. %K A159867 nonn,hard,more %O A159867 1,2 %A A159867 _Eric W. Weisstein_, Apr 24 2009 %E A159867 a(9) and a(10) from _Joseph Myers_, Oct 05 2011 %E A159867 a(11)-a(13) from _Aaron N. Siegel_, May 22 2022