A226281 Least number k such that 3^(2^i) + k is prime for i = 0,1,..,n-1.

2, 2, 2, 2, 58, 440, 18248, 2024098, 4263330280, 22836544460, 40728071843930

Offset

1,1

Comments

Generalized Fermat primes of the form b^(2^i) + k.

Links

Table of n, a(n) for n=1..11.

Example

a(5) = 58 because k = 58 is the minimal k such that  N = 3^(2^i) + k is prime for i = 0, 1, 2 ,3 ,4; N = 61, 67, 139, 6619, 43046779. But 3^(2^5) + 58 is divisible by 37 and three other primes.

Crossrefs

Cf. A129613, A225560.

Sequence in context: A154288 A225057 A084954 * A217993 A049300 A339017

Adjacent sequences: A226278 A226279 A226280 * A226282 A226283 A226284

Keyword

nonn,more

Author

Robin Garcia, Jun 02 2013

Extensions

a(11) from Giovanni Resta, Jun 17 2013

Status

approved