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 A030603 #6 Dec 02 2014 17:41:34
%S A030603 0,1,1,1,1,1,2,2,2,2,2,2,3,3,3,4,4,5,6,7,7,6,6,5,6,5,5,5,5,5,6,6,6,6,
%T A030603 6,6,6,6,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,9,9,9,9,9,10,10,10,11,12,
%U A030603 12,13,13,13,12,12,12,11,12,12,11,11,11,11,11
%N A030603 (# 3's)-(# 4's) in first n terms of A030588.
%t A030603 Accumulate[Which[#==3,1,#==4,-1,True,0]&/@Flatten[Table[ IntegerDigits[ 2n-1,6],{n,50}]]] (* _Harvey P. Dale_, Dec 02 2014 *)
%K A030603 nonn
%O A030603 1,7
%A A030603 _Clark Kimberling_