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 A025612 #19 Jul 06 2025 10:00:26
%S A025612 1,2,4,8,10,16,20,32,40,64,80,100,128,160,200,256,320,400,512,640,800,
%T A025612 1000,1024,1280,1600,2000,2048,2560,3200,4000,4096,5120,6400,8000,
%U A025612 8192,10000,10240,12800,16000,16384,20000,20480,25600,32000,32768,40000,40960
%N A025612 Numbers of form 2^i*10^j, with i, j >= 0.
%H A025612 Amiram Eldar, <a href="/A025612/b025612.txt">Table of n, a(n) for n = 1..10000</a>
%F A025612 Sum_{n>=1} 1/a(n) = (2*10)/((2-1)*(10-1)) = 20/9. - _Amiram Eldar_, Sep 25 2020
%F A025612 a(n) ~ exp(sqrt(2*log(2)*log(10)*n)) / sqrt(20). - _Vaclav Kotesovec_, Sep 25 2020
%F A025612 a(n) = 2^A025639(n) * 10^A025684(n). - _R. J. Mathar_, Jul 06 2025
%t A025612 n = 10^5; Flatten[Table[2^i*10^j, {i, 0, Log2[n]}, {j, 0, Log10[n/2^i]}]] // Sort (* _Amiram Eldar_, Sep 25 2020 *)
%o A025612 (PARI) list(lim)=my(v=List(), N); for(n=0, logint(lim\=1, 10), N=10^n; while(N<=lim, listput(v, N); N<<=1)); Set(v) \\ _Charles R Greathouse IV_, Jan 10 2018
%Y A025612 Subsequence of A000079 and A011557.
%Y A025612 Subsequences: A025621 and A025634.
%K A025612 easy,nonn
%O A025612 1,2
%A A025612 _David W. Wilson_