OFFSET
1,1
COMMENTS
The number k has to be a prime.
a(6) > 10^5. - Robert Price, Oct 08 2012
MATHEMATICA
Select[Prime[Range[PrimePi[1000]]], PrimeQ[36^# - 35^#] &] (* T. D. Noe, Aug 15 2012 *)
PROG
(PARI) is(n)=ispseudoprime(36^n-35^n) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Jean-Louis Charton, Aug 15 2012
EXTENSIONS
a(5) from Robert Price, Oct 08 2012
STATUS
approved