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A064516
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Numbers k such that pi(k^2) is prime.
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1
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2, 6, 17, 28, 33, 34, 40, 41, 43, 50, 53, 54, 57, 59, 60, 69, 75, 76, 79, 97, 100, 107, 109, 110, 111, 113, 119, 127, 137, 142, 157, 161, 178, 198, 202, 232, 238, 246, 262, 263, 267, 273, 276, 282, 287, 300, 302, 306, 317, 322, 335, 339, 341, 344, 348, 353, 365
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OFFSET
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1,1
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LINKS
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PROG
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(PARI) pi(x, c=0) = forprime(p=2, x, c++); c for(n=1, 1000, if(isprime(pi(n^2)), print1(n, " ")))
(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
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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