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 A188196 #7 Mar 30 2012 17:22:57
%S A188196 5,7,10,15,18,29,47,113,163,269,1150,1293,1881,22173,44563,95683,
%T A188196 261955,1179415,1295936,11451171,26867679,42531919,247791599,
%U A188196 429914163,445379527,560533869,619222313,2147478019,2971786617,3474640372
%N A188196 Base-4 Keith numbers.
%C A188196 Keith numbers are described in A007629.
%e A188196 47 is here because, in base 4, 47 is 233 and applying the Keith iteration to this number produces the numbers 2, 3, 3, 8, 14, 25, 47.
%t A188196 IsKeith[n_,b_] := Module[{d, s, k}, d = IntegerDigits[n, b]; s = Total[d]; k = 1; While[AppendTo[d, s]; s = 2 s - d[[k]]; s < n, k++]; s == n]; Select[Range[3,10^5], IsKeith[#,4]&]
%Y A188196 Cf. A007629 (base 10), A162724 (base 2), A187713 (base 5), A188195-A188200.
%K A188196 nonn,base
%O A188196 1,1
%A A188196 _T. D. Noe_, Mar 24 2011