OFFSET
1,1
MAPLE
A275575:=n->`if`(isprime((3^n + 1)/(3 - (-1)^n)), n, NULL): seq(A275575(n), n=1..2*10^3); # Wesley Ivan Hurt, Dec 26 2016
MATHEMATICA
Select[Range[0, 10^3], PrimeQ[(3^# + 1)/(3 - (-1)^#)] &]
PROG
(PARI) isok(n) = isprime( (3^n + 1)/(3 - (-1)^n)); \\ Michel Marcus, Dec 26 2016
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Thomas Ordowski, Dec 25 2016
STATUS
approved