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Numbers k such that 4^k + 33 is prime.
1

%I #16 Nov 28 2023 18:33:00

%S 1,3,6,7,10,15,30,34,54,58,103,105,205,223,279,741,2098,3523,9210,

%T 37674,89895,101509,217123

%N Numbers k such that 4^k + 33 is prime.

%C Contains exactly the halved even terms of A247953.

%C The next terms are > 2*10^5.

%e For k = 30, 4^30 + 33 = 1152921504606847009 is prime.

%t Select[Range[0, 250000], PrimeQ[4^# + 33] &]

%o (Magma) [n: n in [0..700] | IsPrime(4^n+33)]; // _Vincenzo Librandi_, Oct 06 2015

%o (PARI) for(n=1, 1e3, if(isprime(4^n+33), print1(n", "))) \\ _Altug Alkan_, Oct 06 2015

%Y Cf. A247953, A253772 (similar sequence).

%K nonn,more

%O 1,2

%A _Robert Price_, Oct 05 2015

%E a(23) derived from A247953 by _Elmo R. Oliveira_, Nov 28 2023