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 A385028 #20 Aug 18 2025 15:42:39 %S A385028 1,1,4,16,116,903,8551 %N A385028 Number of face-connected components of polyhedral cells in the bisymmetric hendecahedral honeycomb up to translation, rotation, and reflection of the honeycomb. %C A385028 These are "free polyforms" because they are counted up to rotation and reflection. %C A385028 A bisymmetric hendecahedron is an 11-sided polyhedron that is similar to the convex hull of (-2,1,-1), (-2,1,1), (-1,-1,0), (0,-1,-1), (0,-1,1), (0,0,-2), (0,0,2), (0,2,0), (1,-1,0), (2,1,-1), and (2,1,1). %H A385028 Peter Kagey, <a href="/A385028/a385028.gif">Illustration of the a(3)=16 components with three polyhedra</a>. %H A385028 Wikipedia, <a href="https://en.wikipedia.org/wiki/Hendecahedron#Bisymmetric_hendecahedron">Bisymmetric hendecahedron</a> %H A385028 Jiangmei Wu and Guy Inchbald, <a href="https://archive.bridgesmathart.org/2018/bridges2018-483.pdf">Folding Space-Filling Bisymmetric Hendecahedron for a Large-Scale Art Installation</a>, Bridges 2018 Conference Proceedings. %H A385028 Jiangmei Wu, <a href="https://www.jiangmeiwu.com/synergia">Synergia</a> (sculpture made from bisymmetric hendecahedra). %e A385028 For n = 2, the a(2) = 4 distinct compounds of two bisymmetric hendecahedra correspond to placing the four distinct types of faces (square, kite, rhombus, and triangle) together. %Y A385028 Cf. A038119 (cubic), A038173 (rhombic dodecahedral), A038181 (truncated octahedral), A343909 (tetrahedral-octahedral), A365654 (square bipyramidal), A384254 (rectified cubic), A384274 (quarter cubic), A384754 (omnitruncated cubic), A385024 (tetragonal disphenoidal), A385025 (gyrobifastigium), A385026 (hexagonal prismatic), A385027 (triakis truncated tetrahedral), A385267 (half pyramidille), A385268 (oblate cubille), A385269 (quarter cubille), A385270 (elongated dodecahedral), A385271 (hexakis cubic), A385272 (phyllic disphenoidal), A385273 (quarter oblate octahedrille), A385274 (rhombic pyramidal), A385275 (square quarter pyramidille), A385276 (trapezo-rhombic dodecahedral), A385277 (triangular prismatic), A385278 (triangular pyramidille). %K A385028 nonn,hard,more %O A385028 0,3 %A A385028 _Peter Kagey_, Aug 13 2025