%I #31 Nov 16 2023 07:44:16

%S 1,2,3,6,8,9,14,15,42,114,195,392,555,852,1004,1185,2001,2030,2031,

%T 2276,8610,8967,10362,11366,15927,16514,17877,19122,19898,27728,29156,

%U 61275,102981,117663,181560,239922,342789,371226,717200,937776,970406,1102722

%N Numbers k such that 4^k + 3 is prime.

%C The halved even terms of A057732. - _R. J. Mathar_, Feb 26 2008

%e 4^15 + 3 = 1073741827 a prime number.

%o (PARI) is(n)=ispseudoprime(4^n+3) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A057732, A228026 (the actual primes).

%K nonn,more

%O 1,2

%A Herman H. Rosenfeld (herm3(AT)pacbell.net), Dec 28 2003

%E More terms from _Ray Chandler_, Dec 30 2003

%E More terms from _R. J. Mathar_, Feb 26 2008

%E a(33)-a(37) derived from A057732 by _Robert Price_, Apr 26 2014

%E a(38)-a(42) derived from A057732 by _Amiram Eldar_, Nov 16 2023