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 A025611 #27 Jul 06 2025 10:00:07
%S A025611 1,2,4,8,9,16,18,32,36,64,72,81,128,144,162,256,288,324,512,576,648,
%T A025611 729,1024,1152,1296,1458,2048,2304,2592,2916,4096,4608,5184,5832,6561,
%U A025611 8192,9216,10368,11664,13122,16384,18432,20736,23328,26244,32768,36864,41472
%N A025611 Numbers of form 2^i*9^j, with i, j >= 0.
%H A025611 Robert Israel, <a href="/A025611/b025611.txt">Table of n, a(n) for n = 1..10000</a>
%F A025611 Sum_{n>=1} 1/a(n) = (2*9)/((2-1)*(9-1)) = 9/4. - _Amiram Eldar_, Sep 24 2020
%F A025611 a(n) ~ exp(sqrt(2*log(2)*log(9)*n)) / sqrt(18). - _Vaclav Kotesovec_, Sep 24 2020
%F A025611 a(n) = 2^A025638(n) * 9^A025678(n). - _R. J. Mathar_, Jul 06 2025
%p A025611 N:= 10^5: # for terms <= N
%p A025611 sort([seq(seq(2^i*9^j,i=0..ilog2(N/9^j)),j=0..floor(log[9](N)))]); # _Robert Israel_, Mar 23 2020
%t A025611 Take[Union[2^First[#] 9^Last[#]&/@Tuples[Range[0,20],{2}]],50] (* _Harvey P. Dale_, May 26 2011 *)
%t A025611 n = 10^5; Flatten[Table[2^i*9^j, {i, 0, Log[2, n]}, {j, 0, Log[9, n/2^i]}]] // Sort (* _Amiram Eldar_, Sep 24 2020 *)
%Y A025611 Subsequence of A003586.
%K A025611 easy,nonn
%O A025611 1,2
%A A025611 _David W. Wilson_