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 A030592 #6 Jul 22 2012 08:45:17
%S A030592 2,7,13,16,18,19,20,25,31,39,48,57,62,65,66,68,75,84,93,102,111,116,
%T A030592 119,120,122,129,138,142,145,147,148,151,154,156,157,160,163,165,166,
%U A030592 169,170,172,173,174,175,176,178,181,183,184,187
%N A030592 Position of n-th 3 in A030588.
%t A030592 Flatten[Position[Flatten[Table[IntegerDigits[2n-1,6],{n,70}]],3]] (* _Harvey P. Dale_, Jul 22 2012 *)
%K A030592 nonn
%O A030592 1,1
%A A030592 _Clark Kimberling_