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 A258018 #16 Feb 16 2025 08:33:25 %S A258018 0,0,1,0,1,1,3,1,8,5,20,11,62 %N A258018 Number of fusenes of perimeter 2n (not necessarily planar) with bilateral symmetry, counted up to rotations. %C A258018 This sequence counts fusenes which stay the same when flipped over. Fusenes are like polyhexes with additional criteria that no holes are allowed, but on the other hand, helicene-like self-touching or self-overlapping configurations are included in the count here. Cf. the links and further comments at A258019. %C A258018 For n >= 1, a(n) gives the total number of terms k in A258015 with binary width = 2n + 1, or equally, with A000523(k) = 2n. %H A258018 Guo, Hansen, Zheng, <a href="http://dx.doi.org/10.1016/S0166-218X(01)00180-9">Boundary uniqueness of fusenes</a>, Discrete Applied Mathematics 118 (2002), pp. 209-222. %H A258018 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Fusene.html">Fusene</a> %H A258018 Wikipedia, <a href="http://en.wikipedia.org/wiki/Helicene">Helicene</a> %F A258018 Other identities and observations. For all n >= 1: %F A258018 a(n) = 2*A258019(n) - A258017(n). %F A258018 a(n) >= A258205(n). %Y A258018 Cf. A258017, A258019, A258204. %Y A258018 Cf. A258015. %K A258018 nonn,more %O A258018 1,7 %A A258018 _Antti Karttunen_, Jun 02 2015