a(n) = 27*n^2.

Terms

a(0) =0a(1) =27a(2) =108a(3) =243a(4) =432a(5) =675a(6) =972a(7) =1323a(8) =1728a(9) =2187a(10) =2700a(11) =3267a(12) =3888a(13) =4563a(14) =5292a(15) =6075a(16) =6912a(17) =7803a(18) =8748a(19) =9747a(20) =10800a(21) =11907a(22) =13068a(23) =14283a(24) =15552a(25) =16875a(26) =18252a(27) =19683a(28) =21168a(29) =22707