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Prime numbers of the form 4^k + 1.
8

%I #9 Jul 23 2017 21:53:26

%S 2,5,17,257,65537

%N Prime numbers of the form 4^k + 1.

%C Similar to Fermat primes, A019434, a(n) is of the form (2^2)^k + 1.

%t Select[4^Range[0, 100] + 1, PrimeQ]

%Y Cf. A019434, A092506.

%K nonn,more

%O 1,1

%A _Robert Price_, Jul 23 2017