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Numbers k such that both k^2 + 3 and 2^k + 3 are primes.
1

%I #15 Feb 16 2024 15:07:29

%S 2,4,28,784

%N Numbers k such that both k^2 + 3 and 2^k + 3 are primes.

%C Intersection of A057732 and A049422.

%C a(5) > 20000. - _Tyler NeSmith_, May 15 2021

%C a(5) > 2205444, using A057732. - _Michael S. Branicky_, Feb 16 2024

%Y Cf. A000040, A057732, A049422, A329103.

%K nonn,hard,more

%O 1,1

%A _Alex Ratushnyak_, Nov 04 2019