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 A125122 #7 Jan 28 2015 16:19:54
%S A125122 0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,0,1,0,
%T A125122 1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0,
%U A125122 1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0
%N A125122 First differences of A034888.
%C A125122 This sequence is not periodic because log(3)/log(10) is an irrational number. - _T. D. Noe_, Jan 10 2007
%F A125122 a(n)=Number_of_digits{3^(n+1)}-Number_of digits{3^(n)} with n>=0.
%e A125122 a(1)=0 because 3^(1+1)=9 (one digit) 3^1=3 (one digit) and the difference is 0
%e A125122 a(4)=1 because 3^(4+1)=243 (three digits) 3^(4)=81 (two digits) and the difference is 1
%p A125122 P:=proc(n) local i,j,k,w,old; k:=3; for i from 1 by 1 to n do j:=k^i; w:=0; while j>0 do w:=w+1; j:=trunc(j/10); od; if i>1 then print(w-old); old:=w; else old:=w; fi; od; end: P(1000);
%t A125122 Differences[IntegerLength[3^Range[0,110]]] (* _Harvey P. Dale_, Jan 28 2015 *)
%K A125122 easy,nonn,base
%O A125122 0,1
%A A125122 _Paolo P. Lava_ and _Giorgio Balzarotti_, Jan 10 2007