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 A320946 #17 Nov 11 2018 04:51:18 %S A320946 1,2,9,80,1340 %N A320946 a(n) is the number of left-perimeter tiles among all rhombic tilings of the 2n-gon. %C A320946 Also the number of right-perimeter tiles among all rhombic tilings of the 2n-gon. Tiles and polygons all have sides of length 1, as in A006245. %H A320946 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. %F A320946 a(n) = (n-1) * A320945(n). %e A320946 a(4) = 9 because among the eight rhombic tilings of the octagon, 9 left-perimeter rhombi appear. %Y A320946 Cf. A320944, A320945, A006245. %K A320946 nonn,more %O A320946 2,2 %A A320946 _Bridget Tenner_, Oct 24 2018