OFFSET
1,2
COMMENTS
a(27) > 10^5. - Robert Price, Aug 06 2017
As reported by Lelio R Paula in November 2014 at primenumbers.net/prptop, the following three terms are also in this sequence: 127176, 128640, 136434. It is not confirmed that they are the next terms, however. - Robert Price, Aug 06 2017
EXAMPLE
6^1+5=11 and 6^2+5=41, which are both prime, so 1 and 2 are in the sequence. 6^3+5=221 is not prime since it is divisible by 7, so 3 is not in the sequence.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[6^# + 5] &] (* Robert Price, Aug 06 2017 *)
PROG
(PARI) is(n)=ispseudoprime(6^n+5) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Dmitry Kamenetsky, Oct 02 2008
EXTENSIONS
a(21)-a(26) from Robert Price, Aug 06 2017
a(27)-a(30) from Paul Bourdelais, Jan 28 2021
a(31)-a(34) from Paul Bourdelais, Feb 11 2021
STATUS
approved