a(n) = 5*n^3.

Terms

a(0) =0a(1) =5a(2) =40a(3) =135a(4) =320a(5) =625a(6) =1080a(7) =1715a(8) =2560a(9) =3645a(10) =5000a(11) =6655a(12) =8640a(13) =10985a(14) =13720a(15) =16875a(16) =20480a(17) =24565a(18) =29160a(19) =34295a(20) =40000a(21) =46305a(22) =53240a(23) =60835a(24) =69120a(25) =78125a(26) =87880a(27) =98415a(28) =109760a(29) =121945