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 A140639 #8 Jun 20 2017 23:08:35 %S A140639 1,1,1,1,2,5,15,51,179,647,2397,9081,35181,139307,563218 %N A140639 Number of 4-noncrossing RNA structures with arc-length => 4. %C A140639 Table 2, p. 30 of Han and Reidys. See diagrams p. 31. Combinatorial formulas and asymptotic results are also given. %H A140639 Hillary S. W. Han, Christian M. Reidys, <a href="http://arxiv.org/abs/0803.1399">Pseudoknot RNA structures with arc-length => 4</a> %Y A140639 Cf. A004148, A110319, A107905, A110320, A132441. %K A140639 nonn %O A140639 1,5 %A A140639 _Jonathan Vos Post_, Jul 07 2008