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 A300693 #9 Apr 09 2018 10:59:58 %S A300693 0,1,6,42,344,3230,34452 %N A300693 a(n) = number of edges in a concertina n-cube. %C A300693 n-place formulas in first-order logic like Ax Ey P(x, y) can be ordered by implication. This Hasse diagram has A000629(n) vertices and a(n) edges. %C A300693 This is the second diagonal on the right in A300700, the triangle of faces in the concertina n-cube. %C A300693 The corresponding sequence for cocoon concertina n-cubes, which have more internal vertices and edges, is A300694. %H A300693 Tilman Piesk, <a href="https://en.wikiversity.org/wiki/Formulas_in_predicate_logic">Formulas in predicate logic</a> (Wikiversity) %H A300693 Tilman Piesk, Image of a concertina <a href="https://commons.wikimedia.org/wiki/File:Concertina_square_graph.svg">square with 6</a> and <a href="https://commons.wikimedia.org/wiki/File:Concertina_cube_Hasse_diagram.png">cube with 42</a> edges %H A300693 Tilman Piesk, <a href="https://github.com/watchduck/concertina_hypercubes/tree/master/computed_results/hasse">Lists of edges</a> for n=2..5 %H A300693 Tilman Piesk, <a href="https://github.com/watchduck/concertina_hypercubes/blob/master/coordinates_hasse.py">Python code used to generate the sequence</a> %F A300693 a(n) = A300700(n, n-1). %Y A300693 Cf. A300700, A000629, A300694. %K A300693 nonn,more %O A300693 0,3 %A A300693 _Tilman Piesk_, Apr 03 2018