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 A320945 #17 Nov 11 2018 04:51:10 %S A320945 1,1,3,20,268 %N A320945 a(n) is the number of top-perimeter tiles among all rhombic tilings of the 2n-gon. %C A320945 Also the number of bottom-perimeter tiles among all rhombic tilings of the 2n-gon. Tiles and polygons all have sides of length 1, as in A006245. %H A320945 B. E. Tenner, <a href="https://arxiv.org/abs/1811.00082">Tiling-based models of perimeter and area</a>, arXiv:1811.00082 [math.CO], 2018. %e A320945 a(4) = 3 because among the eight rhombic tilings of the octagon, 3 top-perimeter rhombi appear. %Y A320945 Cf. A320944, A320946, A006245. %K A320945 nonn,more %O A320945 2,3 %A A320945 _Bridget Tenner_, Oct 24 2018