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 A249775 Least prime p such that the concatenation of primes from prime(n) to p is prime. 1

%I

%S 3,0,11,19,17,79,23,151,67,53,37,107,47,131,67,71,83,0,79,137,293,131,

%T 89,101,109,113,283,149,12923,149,317,181,1193,157,163,157,163,193,

%U 173,18041,307,269,227,0,2897,211,257,331,359,239,239,251,599,257,263,269,1531,277,313,379,1259

%N Least prime p such that the concatenation of primes from prime(n) to p is prime.

%C a(n) > 40000 or 0 for n = 2, 18, and 44.

%e For n = 3, prime(3) = 5. 57 is not prime. 5711 is prime. Since 5711 = 5//7//11, a(3) = 11.

%o (PARI) a(n)=s=Str(prime(n));forprime(p=prime(n)+1,40000,s=concat(s,p); if(ispseudoprime(eval(s)),return(p)));0

%o for(n=1,50,print1(a(n),", "))

%Y Cf. A249774.

%K nonn,base

%O 1,1

%A _Derek Orr_, Nov 05 2014

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Last modified December 6 22:42 EST 2021. Contains 349567 sequences. (Running on oeis4.)