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A241007 Decimal encoding of the prime factorization of a(n) is a prime.

%I A241007 #11 Aug 16 2014 18:18:41
%S A241007 3,6,7,8,13,19,20,31,35,38,40,43,44,45,56,60,63,65,68,69,96,97,103,
%T A241007 104,109,116,119,122,125,133,138,151,157,159,160,171,174,181,189,193,
%U A241007 204,209,211,212,215,216,220,221,232,241,248,250,254,267,271,273,280
%N A241007 Decimal encoding of the prime factorization of a(n) is a prime.
%C A241007 This sequence gives all arguments for which A067599 is prime: A067599(a(n)) = prime. - _Wolfdieter Lang_, Aug 16 2014
%H A241007 Paolo P. Lava, <a href="/A241007/b241007.txt">Table of n, a(n) for n = 1..1000</a>
%F A241007 Sequence of the members of the set {k >= 2: A067599(k) is a prime} in increasing order. - _Wolfdieter Lang_, Aug 16 2014
%e A241007 Prime factorization of a(4) = 8 is 2^3 and its decimal encoding is A067599(8) = 23 that is prime.
%e A241007 Prime factorization of a(188) = 994 is 2^1*7^1*71^1 and its decimal encoding is  A067599(994) = 2171711 that is prime.
%p A241007 with(numtheory); P:=proc(q) local a,b,c,d,k,j,n;
%p A241007 for n from 1 to q do a:=(ifactors(n)[2]); b:=[];
%p A241007 for k from 1 to nops(a) do b:=[op(b),a[k,1]]; od; b:=sort(b); c:=0;
%p A241007 for k from 1 to nops(b) do d:=1; while b[k]<>a[d,1] do d:=d+1; od;
%p A241007 j:=b[k]*10^(ilog10(a[d,2])+1)+a[d,2];
%p A241007 c:=c*10^(ilog10(j)+1)+j; od; if isprime(c) then print(n);
%p A241007 fi; od; end: P(1000);
%Y A241007 Cf. A067598, A067599.
%K A241007 nonn,easy,base
%O A241007 1,1
%A A241007 _Paolo P. Lava_, Aug 07 2014
%E A241007 Edited: Name n-> a(n), cf. A067599, examples specified. - _Wolfdieter Lang_, Aug 16 2014