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%I #7 Mar 29 2014 13:58:31
%S 4,16,21,27,36,64,256,288,648,729,1024,1444,1458,1764,1936,2304,3125,
%T 4096,4361,5184,6272,7688,8277,9408,11664,16384,18432,19683,22472,
%U 22987,26244,28125,29403,31199,41472,43264,59577,65536,67712,73008
%N The prime factors of n are also prime factors of the decimal encoding (A067599) of the prime factorization of n.
%e 21 = 3^1 * 7^1 has prime factors 3,7, which are also prime factors of the corresponding decimal encoding 3171 = 3^1 * 7^1 * 151^1.
%t (*f gives the decimal encoding of the prime factorization of n*) f[n_] := FromDigits[Flatten[IntegerDigits[FactorInteger[n]]]]; (*g gives the list of prime factors of n*) g[n_] := Module[{a, l, t}, a = FactorInteger[n]; l = Length[a]; Table[a[[i]][[1]], {i, 1, l}]];
%t (*main routine*) j[n] := Module[{l1 = g[n], l2 = g[f[n]]}, (Intersection[l1, l2] == l1)]; Select[Range[2, 10^5], j[ # ] &]
%Y Cf. A067599.
%K nonn,base
%O 1,1
%A _Joseph L. Pe_, Feb 04 2002
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