a(n) = n^3 if n odd, 7*n^3/8 if n even.

Terms

a(0) =0a(1) =1a(2) =7a(3) =27a(4) =56a(5) =125a(6) =189a(7) =343a(8) =448a(9) =729a(10) =875a(11) =1331a(12) =1512a(13) =2197a(14) =2401a(15) =3375a(16) =3584a(17) =4913a(18) =5103a(19) =6859a(20) =7000a(21) =9261a(22) =9317a(23) =12167a(24) =12096a(25) =15625a(26) =15379a(27) =19683a(28) =19208a(29) =24389