A089437 Numbers k such that 4^k + 3 is prime.

1, 2, 3, 6, 8, 9, 14, 15, 42, 114, 195, 392, 555, 852, 1004, 1185, 2001, 2030, 2031, 2276, 8610, 8967, 10362, 11366, 15927, 16514, 17877, 19122, 19898, 27728, 29156, 61275, 102981, 117663, 181560, 239922, 342789, 371226, 717200, 937776, 970406, 1102722

Offset: 1

Author

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

Keywords

• nonn
• more

Comments

The halved even terms of A057732. - R. J. Mathar, Feb 26 2008

Examples

			4^15 + 3 = 1073741827 a prime number.
		

Crossrefs

Cf. A057732, A228026 (the actual primes).

Programs

PARI

is(n)=ispseudoprime(4^n+3) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

More terms from Ray Chandler, Dec 30 2003

More terms from R. J. Mathar, Feb 26 2008

a(33)-a(37) derived from A057732 by Robert Price, Apr 26 2014

a(38)-a(42) derived from A057732 by Amiram Eldar, Nov 16 2023