Search: id:A087368
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%I A087368
%S A087368 3,5,277,353,773,3733,5557,7523,7753,25357,25733,27733,32233,32323,
%T A087368 32533,37273,53233,53353,53377,53777,55733,72337,72727,73757,77377,
%U A087368 77557,232523,272333,275773,322727,327553,327757,333233,352357,353527
%N A087368 Prime index primes (PIPS) whose digits are primes.
%C A087368 Chances are these numbers are infinite since PIPS are infinite.
%H A087368 A. Frank & P. Jacqueroux, <a href="http://paulcooijmans.lunarpages.com/
               oth/intcontest.pdf">International Contest</a>, 2001. Item 12
%e A087368 59 is prime and the 59th prime is 277 and 2,7 are primes.
%o A087368 (PARI) pip(n) = { for(x=1,n, flag=1; y=prime(prime(x)); y2=y; for(j=1,
               length(Str(y)), r = y%10; if(!isprime(r),flag=0); y = floor(y/10); 
               ); if(flag,print1(y2",")); ) }
%Y A087368 Sequence in context: A087367 A058846 A101331 this_sequence A087670 A138584 
               A002427
%Y A087368 Adjacent sequences: A087365 A087366 A087367 this_sequence A087369 A087370 
               A087371
%K A087368 easy,nonn
%O A087368 3,1
%A A087368 Cino Hilliard (hillcino368(AT)gmail.com), Oct 21 2003

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