A217133 Numbers n such that 5^n + 8 is prime.

1, 95, 335, 3155, 28651, 91135

Offset

1,2

Comments

Naturally these numbers are odd since (6-1)^(2n)+8 is divisible by 3. - Bruno Berselli, Oct 04 2012

a(7) > 10^5. - Robert Price, Feb 03 2014

a(7) > 5*10^5. - Tyler NeSmith, Apr 24 2022

Links

Table of n, a(n) for n=1..6.

Mathematica

Select[Range[1, 15000, 2], PrimeQ[5^# + 8] &]

Prog

(PARI) for(n=1, 5*10^3, if(isprime(5^n+8), print1(n", ")))

Crossrefs

Cf. A087885, A089142, A124621.

Sequence in context: A008875 A174157 A200882 * A055823 A116250 A362322

Adjacent sequences: A217130 A217131 A217132 * A217134 A217135 A217136

Keyword

nonn,more

Author

Vincenzo Librandi, Oct 01 2012

Extensions

a(5)-a(6) from Robert Price, Feb 03 2014

Status

approved