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A334170 Emirps containing only the digits 1 and 2.

%I A334170 #18 Nov 08 2020 12:50:40
%S A334170 111211,112111,12122221,12222121,1111122121,1212211111,11121211121,
%T A334170 11212221121,12111212111,12112221211,111122221121,111122222111,
%U A334170 111122222221,111211221221,111212212211,111212222111,111222212111,111222221111,112111211221,112122112211,112122211121
%N A334170 Emirps containing only the digits 1 and 2.
%H A334170 Daniel Starodubtsev, <a href="/A334170/b334170.txt">Table of n, a(n) for n = 1..10000</a>
%t A334170 Union @ Flatten @ Table[FromDigits /@ Select[Tuples[{1, 2}, n] ,PrimeQ @ (m = FromDigits[#]) && # != (r = Reverse[#]) && PrimeQ @ FromDigits[r] &], {n, 12}] (* _Amiram Eldar_, Apr 18 2020 *)
%t A334170 Table[Select[FromDigits/@Tuples[{1,2},n],!PalindromeQ[#]&&AllTrue[ {#,IntegerReverse[ #]},PrimeQ]&],{n,12}]//Flatten (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Nov 08 2020 *)
%o A334170 (PARI) isok(p) = if (isprime(p), my(d=digits(p), rd=Vecrev(d)); (vecsort(d,,8) == [1,2]) && isprime(fromdigits(rd)) && (rd != d));
%o A334170 lista(nn) = {for (n=1, nn, my(vf = vector(n, k, 1)); for (i=1, 2^n-1, my(vpos = select(x->(x==1), Vecrev(binary(i)), 1), nvf = vf); for (i=1, #vpos, nvf[vpos[i]] = 2;); my(x = eval(Str(1, fromdigits(Vecrev(nvf)), 1))); if (isok(x), print1(x, ", "));););} \\ _Michel Marcus_, Apr 18 2020
%Y A334170 Intersection of A007931 and A006567.
%Y A334170 Subsequence of A020450.
%K A334170 nonn,base
%O A334170 1,1
%A A334170 _Daniel Starodubtsev_, Apr 17 2020