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 A161559 #5 Mar 31 2012 12:38:24
%S A161559 2,11,54,136,1473,3483,36244,41086,305728,379955,582669,4540387,
%T A161559 5020443,22096761,24228660,48364856,178868536,234516235,524137295,
%U A161559 1096104266,11627672572,19828856452,31372689367,47247829739,701124643395
%N A161559 Engel expansion of tan(1/2).
%H A161559 <a href="/index/El#Engel">Index to sequences related to Engel expansions</a>
%e A161559 A161011 = 0.546302.... = 1/2+1/(2*11)+1/(2*11*54)+1/(2*11*54*136)+ ...
%t A161559 EngelExp[A_,n_]:=Join[Array[1&,Floor[A]],First@Transpose@NestList[{Ceiling[1/ Expand[ #[[1]]#[[2]]-1]],Expand[ #[[1]]#[[2]]-1]}&,{Ceiling[1/(A-Floor[A])], A-Floor[A]},n-1]]; EngelExp[N[Tan[1/2],6! ],50]
%Y A161559 Cf. A006784.
%K A161559 nonn
%O A161559 1,1
%A A161559 _Vladimir Joseph Stephan Orlovsky_, Jun 13 2009
%E A161559 Example added by _R. J. Mathar_, Oct 04 2009