a(n) = 6^n + 5.

Terms

a(0) =6a(1) =11a(2) =41a(3) =221a(4) =1301a(5) =7781a(6) =46661a(7) =279941a(8) =1679621a(9) =10077701a(10) =60466181a(11) =362797061a(12) =2176782341a(13) =13060694021a(14) =78364164101a(15) =470184984581