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 A086412 #9 Jan 29 2020 04:38:42
%S A086412 0,1,1,1,2,1,1,2,1,2,2,1,1,2,2,2,1,2,1,2,2,1,2,2,2,2,1,1,2,2,2,2,2,1,
%T A086412 2,2,1,2,2,2,1,2,2,2,2,2,2,1,1,2,2,2,2,2,2,1,2,2,2,2,2,1,2,2,1,2,2,2,
%U A086412 2,2,2,2,2,1,2,2,1,2,2,2,2,2,2,1,2,2,2,2,2,2,2,2,1,2,1,2,2,2,2,2,2,2
%N A086412 Number of distinct prime factors of 3-smooth numbers.
%H A086412 Amiram Eldar, <a href="/A086412/b086412.txt">Table of n, a(n) for n = 1..10000</a>
%F A086412 a(n) = A001221(A003586(n));
%F A086412 a(n) <= 2.
%t A086412 s = {}; m = 12; Do[n = 3^k; While[n <= 3^m, AppendTo[s, n]; n*=2], {k, 0, m}]; PrimeNu /@ Union[s] (* _Amiram Eldar_, Jan 29 2020 *)
%Y A086412 Cf. A001221, A003586, A069352, A086414.
%K A086412 nonn
%O A086412 1,5
%A A086412 _Reinhard Zumkeller_, Jul 18 2003