Primes of the form 3^(2n-3)+3^(n-1)+1.A199192Primes of the form 3^(2n-3)+3^(n-1)+1.Terms a(0) =7a(1) =37a(2) =271a(3) =2269a(4) =19927a(5) =129159847a(6) =1162320517External referencesoeis: A199192