a(n) = 729*n^2 + 27.

Terms

a(0) =27a(1) =756a(2) =2943a(3) =6588a(4) =11691a(5) =18252a(6) =26271a(7) =35748a(8) =46683a(9) =59076a(10) =72927a(11) =88236a(12) =105003a(13) =123228a(14) =142911a(15) =164052a(16) =186651a(17) =210708a(18) =236223a(19) =263196a(20) =291627a(21) =321516a(22) =352863a(23) =385668a(24) =419931a(25) =455652a(26) =492831a(27) =531468a(28) =571563a(29) =613116