3^n-th prime.

Terms

a(0) =2a(1) =5a(2) =23a(3) =103a(4) =419a(5) =1543a(6) =5519a(7) =19289a(8) =65687a(9) =220861a(10) =733561a(11) =2412779a(12) =7867547a(13) =25485211a(14) =82064027a(15) =262960091a(16) =839001721a(17) =2666790167a(18) =8448283757a(19) =26684834641a(20) =84064182061a(21) =264194301347a(22) =828513359549