OFFSET
1,2
FORMULA
a(n) = A057221(n)/2. - Joerg Arndt, Aug 28 2015
EXAMPLE
15 is a term because 4^15 + 19 = 1073741843 is prime.
MATHEMATICA
Select[Range[3000], PrimeQ[4^# + 19] &]
PROG
(Magma) [n: n in [0..700] | IsPrime(4^n+19)];
(PARI) is(n)=ispseudoprime(4^n+19) \\ Charles R Greathouse IV, Jun 06 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Jan 16 2015
EXTENSIONS
Three more term (using A057221) from Joerg Arndt, Aug 28 2015
a(14)-a(15) derived from A057221 by Elmo R. Oliveira, Nov 28 2023
STATUS
approved