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 A161181 #8 Feb 12 2014 18:24:28 %S A161181 1,2,10,290,252010,190526868290,108901462620994495704010, %T A161181 35578585682975584013618831758290462042094536290, %U A161181 3797507277602505611886017656109365392377072888898472983341161302567287339676755374368286356010 %N A161181 A117805/3. %F A161181 a(0)=1, a(n)=a(n-1)*(3*a(n-1)-1) %t A161181 NestList[#(3#-1)&,1,10] (* _Harvey P. Dale_, Apr 01 2011 *) %K A161181 easy,nonn %O A161181 0,2 %A A161181 _David Applegate_, Jun 05 2009