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 A085256 #8 Jan 29 2020 04:38:33
%S A085256 2,3,4,8,9,12,16,27,54,64,81,108,144,256,432,512,729,972,1728,2916,
%T A085256 3072,3456,4096,6561,11664,19683,20736,23328,27648,65536,78732,139968,
%U A085256 157464,186624,262144,442368,531441,944784,1062882,1259712,1769472
%N A085256 3-smooth numbers whose arithmetic derivatives are also 3-smooth.
%C A085256 2^i * 3^j is a term iff 3*i + 2*j is 3-smooth, see A067371.
%H A085256 Amiram Eldar, <a href="/A085256/b085256.txt">Table of n, a(n) for n = 1..10000</a>
%e A085256 144 = 2^4 * 3^2: A003415(144) = 384 = 2^7 * 3, therefore 144 is a term.
%t A085256 s = {}; m = 14; Do[n = 3^k; While[n <= 3^m, AppendTo[s, n]; n*=2], {k, 0, m}]; ad[1] = 0; ad[n_] := n * Total @ (Last[#]/First[#] & /@ FactorInteger[n]); Select[Union[s],EulerPhi[6*(ad1 = ad[#])] == 2*ad1 && ad1 > 0 &] (* _Amiram Eldar_, Jan 29 2020 *)
%Y A085256 Cf. A003415, A003586, A067371.
%K A085256 nonn
%O A085256 1,1
%A A085256 _Reinhard Zumkeller_, Aug 11 2003