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 A380360 #13 Jan 26 2025 17:42:47 %S A380360 0,0,0,1,1,2,2,4,7,16,32,76,181,443,1098,2793,7127,18458,48128,126580, %T A380360 334955,892187,2388674,6428489,17377599,47174939,128555088,351580903, %U A380360 964696719,2655197386,7329051870,20284610084,56283140111,156537249660,436338547904,1218824493990,3411297202411 %N A380360 Number of embeddings on the sphere of Halin graphs on n unlabeled nodes up to orientation-preserving homeomorphisms. %C A380360 Halin graphs are planar and 3-connected and can be embedding in the sphere in essentially one way up to mirror symmetry. This sequence counts each graph as either 1 or 2 depending on if it is mirror symmetric. %H A380360 Andrew Howroyd, <a href="/A380360/b380360.txt">Table of n, a(n) for n = 1..1000</a> %H A380360 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HalinGraph.html">Halin Graph</a>. %H A380360 Wikipedia, <a href="https://en.wikipedia.org/wiki/Halin_graph">Halin graph</a>. %o A380360 (PARI) A380360seq(36) \\ See PARI Link in A380362 for program code. %Y A380360 Row sums of A380361. %Y A380360 Antidiagonal sums of A295633. %Y A380360 Cf. A005043, A346779, A380362. %K A380360 nonn %O A380360 1,6 %A A380360 _Andrew Howroyd_, Jan 25 2025