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 A371620 #24 Apr 07 2025 13:59:41 %S A371620 1,1,8,48,266 %N A371620 Fractal sequence based on a heptagon: a(n) = number of unobscured heptagons remaining after completing step n. %C A371620 Start with a single regular heptagon. The heptagon fractal is constructed by taking with the previous completed step, and overlapping it in its entirety to each vertex (excluding the top vertex as they overlap completely). Once constructed, any unobscured heptagons within are counted. "Unobscured" means no lines cross through it, and its shape is regular. See links for images. %H A371620 Gavin Lupo, <a href="/A371620/a371620.png">Heptagon Construction, the initial steps</a> %H A371620 Gavin Lupo, <a href="/A371620/a371620_3.png">Step 5</a> %e A371620 Start with a(1) = 1 unobscured heptagon. For the next step, take step 1's entire shape and place it at each vertex. Although the total number of heptagons is 7, only 1 unobscured heptagon remains, so a(2) = 1. %Y A371620 Cf. A371536. %K A371620 nonn,more %O A371620 1,3 %A A371620 _Gavin Lupo_, Mar 29 2024