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 A063550 #22 Mar 13 2018 05:46:17 %S A063550 1,1,3,3,14,12,79,56,497,311 %N A063550 Largest number of crossing-free matchings on a set S of n points in the plane, that is, a set of floor(n/2) pairwise non-intersecting segments with endpoints in S having no endpoint in common. %H A063550 O. Aichholzer and H. Krasser, <a href="http://www.ist.tugraz.at/publications/oaich/psfiles/ak-psotd-01.ps.gz">The point set order type data base: a collection of applications and results</a>, pp. 17-20 in Abstracts 13th Canadian Conference on Computational Geometry (CCCG '01), Waterloo, Aug. 13-15, 2001. %H A063550 M. Sharir and E. Welzl. <a href="http://www.inf.ethz.ch/personal/emo/PublFiles/CrossFreeMatch_SODA17th_06.pdf">On the Number of Crossing-Free Matchings, (Cycles, and Partitions)</a> %e A063550 The Sharir link contains an image (Figure 1) of a placement of 6 points in the plane such that 12 of their perfect matchings are crossing-free, demonstrating that a(6) >= 12. - _Nathaniel Johnston_, Nov 17 2014 %Y A063550 Cf. A063549. %K A063550 nonn,nice,hard,more %O A063550 1,3 %A A063550 _N. J. A. Sloane_, Aug 14 2001 %E A063550 a(1) = a(2) = 1 inserted by _Nathaniel Johnston_, Nov 17 2014 %E A063550 Name clarified by _Manfred Scheucher_, Mar 12 2018