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%I #18 Mar 02 2024 04:01:21
%S 1,3,9,15,37,85,133,225,1233,12793,108889
%N Numbers k such that 4^k + k is prime.
%C a(11) > 20000. - _Jinyuan Wang_, Feb 01 2020
%t Do[ If[ PrimeQ[ 4^n + n ], Print[ n ] ], {n, 0, 3000} ]
%o (PARI) is(n)=ispseudoprime(4^n+n) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y Cf. A052007, A057900.
%Y Cf. A158879 (4^n + n).
%K nonn,more
%O 1,2
%A _Robert G. Wilson v_, Nov 16 2000
%E a(10) from _Jinyuan Wang_, Feb 01 2020
%E a(11) from _Hugo Pfoertner_, Mar 02 2024
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