a(1)=27; if n = Product p_i^e_i, n>1, then a(n) = Product p_{i+2}^{e_i+2}.

Terms

a(0) =27a(1) =125a(2) =343a(3) =625a(4) =1331a(5) =42875a(6) =2197a(7) =3125a(8) =2401a(9) =166375a(10) =4913a(11) =214375a(12) =6859a(13) =274625a(14) =456533a(15) =15625a(16) =12167a(17) =300125a(18) =24389a(19) =831875a(20) =753571a(21) =614125a(22) =29791a(23) =1071875a(24) =14641a(25) =857375a(26) =16807a(27) =1373125a(28) =50653a(29) =57066625