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Numbers k such that (6^k + 6*k)/6 is prime.
2

%I #4 Feb 25 2024 00:11:06

%S 1,5,7,1003,40513

%N Numbers k such that (6^k + 6*k)/6 is prime.

%C If it exists, a(6) > 62000.

%o (PARI) is(n) = ispseudoprime(6^(n-1)+n)

%Y Cf. A058828, A221908, A226200.

%K nonn,hard,more

%O 1,2

%A _Hugo Pfoertner_, Feb 24 2024