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A064516 Numbers n such that pi(n^2) is prime. 1

%I

%S 2,6,17,28,33,34,40,41,43,50,53,54,57,59,60,69,75,76,79,97,100,107,

%T 109,110,111,113,119,127,137,142,157,161,178,198,202,232,238,246,262,

%U 263,267,273,276,282,287,300,302,306,317,322,335,339,341,344,348,353,365

%N Numbers n such that pi(n^2) is prime.

%H Harry J. Smith, <a href="/A064516/b064516.txt">Table of n, a(n) for n = 1..1000</a>

%o (PARI) pi(x, c=0) = forprime(p=2,x,c++); c for(n=1,1000, if(isprime(pi(n^2)),print1(n," ")))

%o (PARI) { n=0; default(primelimit, 3500000000); for (m=1, 10^9, if (isprime(primepi(m^2)), write("b064516.txt", n++, " ", m); if (n==1000, break)) ) } \\ _Harry J. Smith_, Sep 17 2009

%Y Cf. A000720.

%K easy,nonn

%O 1,1

%A _Jason Earls_, Oct 07 2001

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Last modified October 16 09:02 EDT 2021. Contains 348041 sequences. (Running on oeis4.)