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 A161618 #5 Mar 31 2012 12:38:24
%S A161618 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%T A161618 1,1,3,3,7,9,23,43,128,1847,10674,256943,951850,1361782,1407741,
%U A161618 2143780,3702054,13341664,17967518,101541311,159133300,246184506,3508330471
%N A161618 Engel expansion of Pi^Pi.
%H A161618 <a href="/index/El#Engel">Index to sequences related to Engel expansions</a>
%e A161618 A073233 = 36.462... = 1/1 +1/1 +1/1 +... +1/(1*3) +1/(1*3*3) +1/(1*3*3*7) +1/(1*3*3*7*9) +...
%t A161618 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[Pi^Pi,7! ],50]
%K A161618 nonn
%O A161618 1,37
%A A161618 _Vladimir Joseph Stephan Orlovsky_, Jun 14 2009
%E A161618 Example added by _R. J. Mathar_, Oct 02 2009