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%I #5 Nov 21 2013 12:48:43
%S 1,1,1,1,2,2,4,7,13,25,50,99,196,392,783,1566,3131,6261,12521,25042,
%T 50084,100166,200332,400663,801325,1602649,3205298,6410595,12821190,
%U 25642379,51284758
%N Number of digits in numbers appearing in A108225.
%C Starting with a(14)=783, a(n) = 2*a(n-1) - (1 or 0).
%e A109070(10)=50 because A108225(10)=16217557574922386301420536972254869595782763547562 has 50 digits.
%t 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 Cf. A108225.
%K base,nonn
%O 0,5
%A _Zak Seidov_, Jun 18 2005