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 A005506 M2676 #37 Feb 23 2021 10:07:00 %S A005506 1,3,7,19,57,176,557,1806,5954,19897,67235,229366,788688,2730810, %T A005506 9512107,33309444,117190184,414039578,1468349782,5225201321, %U A005506 18651958885,66769742002,239643164237,862168692562,3108716586702,11232127258416,40660388117380,147453014455094 %N A005506 Number of unrooted triangulations with reflection symmetry of a pentagon with n internal nodes. %C A005506 These are also called [n,2]-triangulations. %D A005506 C. F. Earl and L. J. March, Architectural applications of graph theory, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979. %D A005506 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A005506 Andrew Howroyd, <a href="/A005506/b005506.txt">Table of n, a(n) for n = 0..200</a> %H A005506 C. F. Earl and L. J. March, <a href="/A005500/a005500_1.pdf">Architectural applications of graph theory</a>, pp. 327-355 of R. J. Wilson and L. W. Beineke, editors, Applications of Graph Theory. Academic Press, NY, 1979. (Annotated scanned copy) %H A005506 C. F. Earl & N. J. A. Sloane, <a href="/A005500/a005500.pdf">Correspondence, 1980-1981</a> %F A005506 a(n) = 2 * A005501(n) - A002711(n) (based on _Max Alekseyev_'s formula, cf. A005501). %Y A005506 Column k=2 of the array in A169809. %Y A005506 Cf. A002711, A005501. %K A005506 nonn %O A005506 0,2 %A A005506 _N. J. A. Sloane_ %E A005506 a(6)-a(11) from _Altug Alkan_ and _Manfred Scheucher_, Mar 08 2018 %E A005506 Name clarified and terms a(12) and beyond from _Andrew Howroyd_, Feb 21 2021