%I
%S 4,8,16,22,32,44,64,88,121,128,176,242,256,352,422,484,512,704,844,
%T 968,1024,1331,1408,1688,1936,2048,2321,2662,2816,3376,3872,4096,4222,
%U 4442,4642,5324,5632,6752,7744,8192,8444,8884,9284,10648,11264,13504,14641,15488,16384
%N Composite numbers k such that the digits of the prime factors of k are either 1 or 2.
%C All terms are a product of at least two terms of A020450.  _Michel Marcus_, Oct 02 2020
%H David A. Corneth, <a href="/A036302/b036302.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from Alois P. Heinz)
%H <a href="/index/Pri#prime_factors">Index entries sequences related to prime factors</a>
%F Sum_{n>=1} 1/a(n) = Product_{p in A020450} p/(p1)  Sum_{p in A020450} 1/p  1 = 0.616325...  _Amiram Eldar_, Oct 14 2020
%e 422 = 2 * 211 is in the sequence as the digits of its prime factors 2 and 211 are either 1 or 2.  _David A. Corneth_, Sep 26 2020
%t Select[Range[2,14650],!PrimeQ[#] && Complement[Flatten[IntegerDigits[First/@FactorInteger[#]]],{1,2}]=={} &] (* _Jayanta Basu_, May 25 2013 *)
%o (MAGMA) [k:k in [2..15000] not IsPrime(k) and forall{a: a in PrimeDivisors(k)Intseq(a) subset {1,2}}]; // _Marius A. Burtea_, Oct 08 2019
%Y Cf. A003596 (a subsequence), A020450, A036303A036325.
%K nonn,base
%O 1,1
%A _Patrick De Geest_, Dec 15 1998
