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%I #30 Dec 22 2024 10:07:28
%S 1,3,37,45,597,1131,14203,112539
%N Numbers k such that 8^k - k is prime.
%C a(8) > 41000. - _Giovanni Resta_, Apr 07 2013
%C a(9) > 2*10^5. - _Robert Price_, Jan 19 2014
%o (Java)
%o import java.math.BigInteger;
%o public class A224471 {
%o public static void main (String[] args) {
%o BigInteger b8 = BigInteger.valueOf(8);
%o BigInteger m = BigInteger.valueOf(64);
%o for(long n=1; ; n+=2) {
%o BigInteger b = b8.subtract(BigInteger.valueOf(n));
%o if (b.isProbablePrime(2)) {
%o if (b.isProbablePrime(80))
%o System.out.printf("%d\n", n);
%o }
%o b8 = b8.multiply(m);
%o }
%o }
%o }
%o (PARI) forstep(n=1,10^4,2,if(ispseudoprime(8^n-n),print1(n,", "))); /* _Joerg Arndt_, Apr 07 2013 */
%Y Cf. A048744, A058037, A057908, A058046, A058829, A224470, A224469, A224469.
%K nonn,hard,more,changed
%O 1,2
%A _Alex Ratushnyak_, Apr 06 2013
%E a(7) from _Giovanni Resta_, Apr 07 2013
%E a(8) from _Robert Price_, Jan 19 2014