A077375 Numbers k such that 2^k + prime(k) is prime.

2, 3, 4, 5, 12, 13, 14, 23, 57, 106, 226, 227, 311, 373, 1046, 1298, 1787, 1952, 2130, 2285, 2670, 3254, 3642, 4369, 13559, 33418, 66830, 213810

Offset: 1

Author

Jason Earls, Nov 30 2002

Keywords

• nonn
• more

Comments

All terms < 5000 correspond to certified primes (Primo 2.2.0 beta). - Ryan Propper, Aug 08 2005

Examples

			2^12 + prime(12) = 4096 + 43 = 4139 is a prime, so 12 is a term.
		

Links

• H. Lifchitz, Mersenne and Fermat primes field

Crossrefs

Corresponding prime(k) are in A242944.

Cf. A078583, A078686.

Extensions

a(25)-a(26) from Ryan Propper, Aug 08 2005

a(27) from Henri Lifchitz added by Jason Earls, Jan 12 2008

a(28) from Michael S. Branicky, Jun 01 2025