A090875 a(n) is the smallest number m such that m^(2^k) + 2^(2^k) is prime for k=0,1,...,n.

1, 1, 1, 1, 1, 2321204055, 37185086099807

Offset: 0

Author

Farideh Firoozbakht, Feb 06 2004

Keywords

• nonn

Comments

The first five terms of this sequence correspond to Fermat primes.

According to the answers to Prime Puzzle 399 (see link), a(6) is larger than 2.3*10^12. - M. F. Hasler, Aug 02 2007

Examples

			a(5)=2321204055 because 2321204055 is the smallest number m such that m^(2^k) + 2^(2^k) is prime for k=0,1,2,3,4 and 5.
		

Links

• Carlos Rivera (ed.), Puzzle 399. Some more terms, The Prime Puzzles and Problems Connection.

Crossrefs

Cf. A090872, A090873, A090874.

Extensions

a(6) found by Kellen Shenton sent in by Jeppe Stig Nielsen, Apr 06 2022