OFFSET
1,1
EXAMPLE
3*1+1=4 is not prime (omitted).
a(1)=2 because 3*2+1=7 is prime.
a(2)=3 because 3*2*3+1=19 is prime.
MATHEMATICA
k = 3; a = {}; Do[If[PrimeQ[k*n + 1], k = k*n; AppendTo[a, n]], {n, 1, 3000}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Artur Jasinski, Sep 19 2008
EXTENSIONS
Definition corrected by Georg Fischer, Jun 18 2021
STATUS
approved