a(n) = (9*n + 3)^3.

Terms

a(0) =27a(1) =1728a(2) =9261a(3) =27000a(4) =59319a(5) =110592a(6) =185193a(7) =287496a(8) =421875a(9) =592704a(10) =804357a(11) =1061208a(12) =1367631a(13) =1728000a(14) =2146689a(15) =2628072a(16) =3176523a(17) =3796416a(18) =4492125a(19) =5268024a(20) =6128487a(21) =7077888a(22) =8120601a(23) =9261000a(24) =10503459a(25) =11852352a(26) =13312053a(27) =14886936a(28) =16581375a(29) =18399744