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 A129886 #5 Mar 30 2013 04:47:10
%S A129886 1,0,1,1,6,4,25,20
%N A129886 Sequence a_{h_n} arising in enumeration of arrays of directed blocks (see Quaintance reference for precise definition), where a_n = A129878, h_n = A129874.
%D A129886 Jocelyn Quaintance, Combinatoric Enumeration of Two-Dimensional Proper Arrays, Discrete Math., 307 (2007), 1844-1864.
%F A129886 See Quaintance reference for generating functions that produce A129872-A129886.
%K A129886 nonn,more
%O A129886 1,5
%A A129886 _N. J. A. Sloane_, May 26 2007