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A224471
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Numbers n such that 8^n - n is prime.
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3
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OFFSET
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1,2
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COMMENTS
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LINKS
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PROG
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(Java)
import java.math.BigInteger;
public static void main (String[] args) {
BigInteger b8 = BigInteger.valueOf(8);
BigInteger m = BigInteger.valueOf(64);
for(long n=1; ; n+=2) {
BigInteger b = b8.subtract(BigInteger.valueOf(n));
if (b.isProbablePrime(2)) {
if (b.isProbablePrime(80))
System.out.printf("%d\n", n);
}
b8 = b8.multiply(m);
}
}
}
(PARI) forstep(n=1, 10^4, 2, if(ispseudoprime(8^n-n), print1(n, ", "))); /* Joerg Arndt, Apr 07 2013 */
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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