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 A302205 #8 Apr 26 2018 11:03:16
%S A302205 0,1,20,21,400,401,420,421,8000,8001,8020,8021,8400,8401,8420,8421,
%T A302205 160000,160001,160020,160021,160400,160401,160420,160421,168000,
%U A302205 168001,168020,168021,168400,168401,168420,168421,3200000,3200001,3200020,3200021,3200400,3200401,3200420,3200421,3208000,3208001,3208020,3208021,3208400,3208401,3208420,3208421,32160000
%N A302205 Let the binary expansion of n be [b_d, b_{d-1}, ..., b_3, b_2, b_1, b_0]_2, where (if n>0) b_d = 1, b_i = 0 or 1 for i<d. To get a(n) concatenate the decimal numbers 2^(b_i) (if b_i = 1) or 0 (if b_i = 0).
%C A302205 First differs from A063012 (which uses base 20) at n = 48, where A063012(48) = 3360000, whereas here a(48) = 32160000.
%e A302205 48_10 = 110000_2, so a(48) is the concatenation of 32, 16, 0, 0, 0, 0 = 32160000.
%Y A302205 Cf. A063012.
%K A302205 nonn,base
%O A302205 0,3
%A A302205 _N. J. A. Sloane_, Apr 26 2018
%E A302205 More than the usual number of terms are displayed in order to distinguish this from A063012.