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A087368 Prime-indexed primes (PIPs) whose digits are all primes. 1

%I #16 Apr 04 2023 17:41:44

%S 3,5,277,353,773,3733,5557,7523,7753,25357,25733,27733,32233,32323,

%T 32533,37273,53233,53353,53377,53777,55733,72337,72727,73757,77377,

%U 77557,232523,272333,275773,322727,327553,327757,333233,352357,353527

%N Prime-indexed primes (PIPs) whose digits are all primes.

%C Chances are these numbers are infinite since PIPs are infinite.

%H A. Frank & P. Jacqueroux, <a href="http://www.paulcooijmans.com/others/intcontest.pdf">International Contest</a>, 2001. Item 12

%e 59 is prime, the 59th prime is 277, and 2 and 7 are primes.

%o (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 Intersection of A006450 and A046034.

%K easy,nonn,base

%O 3,1

%A _Cino Hilliard_, Oct 21 2003

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)