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 A030601 #6 Jan 30 2015 18:58:48
%S A030601 1,1,1,2,3,4,4,5,5,5,6,6,6,6,6,6,7,7,7,7,7,7,8,8,8,8,8,8,9,9,9,9,9,10,
%T A030601 9,10,11,10,10,11,10,10,11,12,13,14,15,15,16,17,17,18,18,19,20,20,20,
%U A030601 21,21,21,22,22,23,24,24,24,25,25,25,26,26,27
%N A030601 a(n)=(# 1's)-(# 0's) in first n terms of A030588.
%t A030601 Accumulate[Which[#==1,1,#==0,-1,True,0]&/@Flatten[Table[ IntegerDigits[ 2n-1,6],{n,50}]]] (* _Harvey P. Dale_, Jan 30 2015 *)
%K A030601 nonn
%O A030601 1,4
%A A030601 _Clark Kimberling_