OFFSET
1,1
COMMENTS
All terms are primes.
No other terms < 10^5.
MAPLE
A128027:=n->`if`(isprime((11^n-3^n)/8), n, NULL): seq(A128027(n), n=1..1000); # Wesley Ivan Hurt, Nov 19 2014
MATHEMATICA
k=8; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]
Do[If[PrimeQ[(11^n - 3^n)/8], Print[n]], {n, 10^4}] (* Ryan Propper, Mar 17 2007 *)
Select[Prime[Range[1200]], PrimeQ[(11^# - 3^#)/8] &] (* Vincenzo Librandi, Nov 20 2014 *)
PROG
(Magma) [p: p in PrimesUpTo(400) | IsPrime((11^p-3^p) div 8)]; // Vincenzo Librandi, Nov 20 2014
(PARI) is(n)=ispseudoprime((11^n - 3^n)/8) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 11 2007
EXTENSIONS
a(8) from Ryan Propper, Mar 17 2007
a(9) from Farideh Firoozbakht, Apr 04 2007
a(10)=13103, a(11)=90397 from Robert Price, Apr 24 2011
STATUS
approved