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 A085010 #7 Mar 30 2012 18:39:18 %S A085010 1,3,13,209,53505,3506503681,15060318633198616577, %T A085010 277813843495134114797235287762174738433, %U A085010 94535152227927400227782074307303551040545228366095741656402842333161034088449 %N A085010 a(n)=2^(2^n)*sum(k=0,n,1/2^(2^k)). %F A085010 a(n)=A074854(2^n)=; a(n)=floor(c*2^(2^n)) where c=sum(k>=0, 1/2^(2^k))=0.81642150902... %F A085010 a(n + 1) = 1 + a(n)*2^(2^n), a(0) = 1 [From Peter Moxey (pmoxey(AT)live.com), Mar 14 2010] %Y A085010 Cf. A007404. %K A085010 nonn %O A085010 0,2 %A A085010 _Benoit Cloitre_, Jun 19 2003