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 A063139 #3 Mar 30 2012 17:30:32
%S A063139 9,15,21,27,33,39,45,49,51,57,63,69,75,81,87,93,99,105,111,117,123,
%T A063139 129,135,141,147,153,159,165,171,177,183,189,195,201,207,213,219,225,
%U A063139 231,237,243,249,255,261,267,273,279,285,291,297
%N A063139 Composite numbers which in base 3 contain their largest proper factor as a substring.
%t A063139 Do[ If[ !PrimeQ[ n ] && StringPosition[ ToString[ FromDigits[ IntegerDigits[ n, 3 ] ] ], ToString[ FromDigits[ IntegerDigits[ Divisors[ n ] [ [ -2 ] ], 3 ] ] ] ] != {}, Print[ n ] ], {n, 2, 10^2} ]
%Y A063139 Cf. A062238.
%K A063139 base,nonn
%O A063139 1,1
%A A063139 _Robert G. Wilson v_, Aug 08 2001