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 A069025 #3 Dec 05 2013 19:55:14
%S A069025 1,2,0,4,32,0,16,8,0,64,128,0,256,2048,0,0,0,0,4096,8192,0,16384,0,0,
%T A069025 65536,32768,0,0,524288,0,1048576,0,0,0,134217728,0,16777216,0,0,
%U A069025 67108864,8388608,0,268435456,0,0,4398046511104,2147483648,0,0
%N A069025 Smallest power of 2 with digital sum (A007953) n, or 0 if no such number exists.
%C A069025 a(3k)=0. In general about half the entries are nonzero.
%e A069025 Both 2^4=16 and 2^10=1024 have a digital sum of 7 but 2^4 is the smaller so it is the one presented.
%t A069025 a = Table[0, {50}]; Do[b = Plus @@ IntegerDigits[2^n]; If[b < 51 && a[[b]] == 0, a[[b]] = 2^n], {n, 0, 10^4}]; a
%Y A069025 Cf. A007632.
%K A069025 base,nonn
%O A069025 1,2
%A A069025 _Amarnath Murthy_, Apr 02 2002
%E A069025 Edited by _Robert G. Wilson v_, Nov 05 2002