a(n) = (9*n)^2.

Terms

a(0) =0a(1) =81a(2) =324a(3) =729a(4) =1296a(5) =2025a(6) =2916a(7) =3969a(8) =5184a(9) =6561a(10) =8100a(11) =9801a(12) =11664a(13) =13689a(14) =15876a(15) =18225a(16) =20736a(17) =23409a(18) =26244a(19) =29241a(20) =32400a(21) =35721a(22) =39204a(23) =42849a(24) =46656a(25) =50625a(26) =54756a(27) =59049a(28) =63504a(29) =68121