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 A228118 #18 Mar 24 2018 16:00:05
%S A228118 1,3,5,7,11,13,17,31,37,71,73,79,97,99,113,117,131,135,153,171,199,
%T A228118 311,315,333,337,351,373,513,531,555,577,711,733,757,775,777,919,991,
%U A228118 999,1113,1131,1155,1179,1197,1311,1359,1377,1395,1515,1539,1551,1557
%N A228118 Numbers consisting of only odd digits such that no permutation of its digits yields a semiprime.
%C A228118 This is to A228096 as A001358 Semiprimes (or biprimes): products of two primes is to A000040 Primes. No more below 1111 = 11 * 101.
%H A228118 T. D. Noe, <a href="/A228118/b228118.txt">Table of n, a(n) for n = 1..1000</a>
%e A228118 117 is in this sequence because 117 = 3^2 * 13; 171 = 3^2 * 19; and 711 = 3^2 * 79.
%t A228118 fQ[n_] := Block[{id = IntegerDigits@ n}, Union[ OddQ[id]][[1]] && !MemberQ[ Union[ PrimeOmega[ FromDigits@# & /@ Permutations[id]]], 2]]; Select[ Range[1, 1000, 2], fQ] (* _Robert G. Wilson v_, Aug 11 2013 *)
%t A228118 npdsQ[n_]:=Module[{idn=IntegerDigits[n]},AllTrue[idn,OddQ]&&Count[ FromDigits/@ Permutations[idn],_?(PrimeOmega[#]==2&)]==0]; Select[Range[ 1600],npdsQ] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Mar 24 2018 *)
%Y A228118 Cf. A001358, A014261, A228096.
%K A228118 nonn,base,easy
%O A228118 1,2
%A A228118 _Jonathan Vos Post_, Aug 10 2013