OFFSET
1,1
COMMENTS
a(30) > 450,000. - Robert Price, Oct 04 2018
EXAMPLE
2 is in the sequence because (4^2 + 23)/3 = 13 is prime.
3 is in the sequence because (4^3 + 23)/3 = 29 is prime.
MATHEMATICA
Select[Range[0, 5000], PrimeQ[(4^# + 23)/3] &]
PROG
(Magma) [n: n in [0..1500] | IsPrime((4^n+23) div 3)];
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Aug 27 2015
EXTENSIONS
a(17)-a(28) from Robert Price, Feb 01 2017
a(29) from Robert Price, Oct 04 2018
STATUS
approved