OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
10=2*5 and (10-1)/3=3 prime, 22=2*11 and (22-1)/3=7 prime.
MATHEMATICA
Reap[Do[If[PrimeQ[(a=1+3*Prime[k])/2], Sow[a]], {k, 1000}]][[2, 1]]
PROG
(PARI) isok(n) = (bigomega(n)==2) && (((n-1) % 3)==0) && isprime((n-1)/3); \\ Michel Marcus, Sep 07 2016
(PARI) is(n)=n%3==1 && isprime(n\3) && bigomega(n)==2 \\ Charles R Greathouse IV, Sep 07 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 07 2016
STATUS
approved