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 A102252 #7 Mar 28 2015 22:10:57
%S A102252 1,2,4,8,16,21,24,248,481,681,6212,16212,42421,242484,842484,8168168,
%T A102252 48168162,121621216,816212162,1242421242,4212162124,24212424848,
%U A102252 42484842421,242484842484,816816848168,1684842484816,8168481681621
%N A102252 Slowest increasing sequence beginning with 1 whose digits satisfy the rule d*2.
%C A102252 Same digits as A061581.
%F A102252 d*2, beginning with 1.
%e A102252 Read a(5)=16, which produces first digit of a(6)=2 because 1*2=2 and second digit of a(6)=1 and first digit of a(7)=2 because 6*2=12.
%t A102252 t = Flatten[ NestList[ Function[x, Flatten[ IntegerDigits[2IntegerDigits[ x]]]], 1, 17]]; a = 0; l = {}; Do[k = 1; While[fd = FromDigits[ Take[t, k]]; a >= fd, k++ ]; t = Drop[t, k]; AppendTo[l, fd]; a = fd, {n, 27}]; l (* _Robert G. Wilson v_, Feb 21 2005 *)
%Y A102252 Cf. A061581.
%K A102252 base,easy,nonn
%O A102252 1,2
%A A102252 _Alexandre Wajnberg_ and _Eric Angelini_, Feb 18 2005
%E A102252 More terms from _Robert G. Wilson v_, Feb 21 2005