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 A181559 #13 Oct 01 2012 16:41:33 %S A181559 3311,23177,27181,32153,36421,41237,53977,86507,110971,125069,142373, %T A181559 162239,190267,208579,254947,256413,288659,298991,353683,377839, %U A181559 400631,500981,543337,593747,769239,776797,853811,875483,901949,964481,996611,1053787,1135673 %N A181559 Numbers with three distinct prime factors (each of which may or may not be repeated) which when concatenated in any order form a prime number. %C A181559 This is a superset of A180679 because in this sequence, unlike in A180679, any of the prime factors may (but need not) be repeated as a factor. %t A181559 okQ[n_] := Module[{pfs = Transpose[FactorInteger[n]][[1]]}, Length[pfs] == 3 && And @@ PrimeQ[FromDigits /@ (Flatten /@ (IntegerDigits /@ Permutations[pfs]))]]; Select[Range[2100000], okQ] %Y A181559 Cf. A180679, A217263, A217264, A217265. %K A181559 nonn,base %O A181559 1,1 %A A181559 _Harvey P. Dale_, Jan 29 2011