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 A265686 #19 Feb 10 2019 01:56:25 %S A265686 1,3,7,10,63,157,456,1830,0,8538,23114,61804,165123,0,2339000 %N A265686 Number of shapes of grid-filling curves of order 6*n+1 (on the tri-hexagonal grid) with turns by +-60 and +-120 degrees that are generated by Lindenmayer-systems with just one symbol apart from the turns. %C A265686 Such curves exist only for n such that 6*n+1 is a term of A003136, these values 6*n+1 are given in A260682. %C A265686 The first such curve, the only one of order 7, was discovered by Jeffrey Ventrella, see page 105 in the Ventrella reference. %H A265686 Joerg Arndt, <a href="https://arxiv.org/abs/1607.02433">Plane-filling curves on all uniform grids</a>, arXiv preprint arXiv:1607.02433 [math.CO], 2016. %H A265686 Jeffrey J. Ventrella, <a href="http://archive.org/download/BrainfillingCurves-AFractalBestiary/">Brain-Filling Curves: A Fractal Bestiary</a>, LuLu.com, (2012). %Y A265686 Cf. A234434 (shapes on the triangular grid), A265685 (shapes on the square grid). %K A265686 nonn,hard,more %O A265686 1,2 %A A265686 _Joerg Arndt_, Dec 13 2015 %E A265686 a(11) - a(15) from _Joerg Arndt_, Feb 10 2019