A161719 Least number k such that 7^(2^i) + k is prime for i = 0,1,..,n-1.

4, 4, 10, 40, 990, 8712, 1691820, 69466840, 6173190532, 4139897208540

Offset: 1

Author

Robin Garcia, Jun 16 2013

Keywords

• nonn
• more

Examples

			a(5) = 990 because k = 990 is the minimal k such that N = 7^(2^i) + k is prime for i = 0, 1, 2, 3, 4; N = 997, 1039, 3391, 5765791, 33232930570591. But 7^(2^5) + 990 is divisible by 37 and four other primes.
		

Crossrefs

Cf. A129613, A225560 A226281, A226707.

Extensions

a(10) from Giovanni Resta, Jun 16 2013