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 A109070 #5 Nov 21 2013 12:48:43
%S A109070 1,1,1,1,2,2,4,7,13,25,50,99,196,392,783,1566,3131,6261,12521,25042,
%T A109070 50084,100166,200332,400663,801325,1602649,3205298,6410595,12821190,
%U A109070 25642379,51284758
%N A109070 Number of digits in numbers appearing in A108225.
%C A109070 Starting with a(14)=783, a(n) = 2*a(n-1) - (1 or 0).
%e A109070 A109070(10)=50 because A108225(10)=16217557574922386301420536972254869595782763547562 has 50 digits.
%t A109070 nxt[{a_,b_}]:={b,((a+b)(b-a+1))/2}; Join[{1},IntegerLength/@ Transpose[ NestList[nxt,{0,2},31]][[2]]] (* _Harvey P. Dale_, Feb 14 2012 *)
%Y A109070 Cf. A108225.
%K A109070 base,nonn
%O A109070 0,5
%A A109070 _Zak Seidov_, Jun 18 2005