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 A007859 #15 Apr 05 2019 10:00:20 %S A007859 0,1,4,18,84,405,2002,10101,51844,269994,1423784,7590044,40846390, %T A007859 221650195,1211606190 %N A007859 Number of matchings in rooted plane trees on n nodes. %H A007859 M. Klazar, <a href="http://dx.doi.org/10.1006/eujc.1995.0095">Twelve countings with rooted plane trees</a>, European Journal of Combinatorics 18 (1997), 195-210; Addendum, 18 (1997), 739-740. %H A007859 <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a> %K A007859 nonn,more %O A007859 1,3 %A A007859 _Martin Klazar_