a(n) = 65*n^2.

Terms

a(0) =65a(1) =260a(2) =585a(3) =1040a(4) =1625a(5) =2340a(6) =3185a(7) =4160a(8) =5265a(9) =6500a(10) =7865a(11) =9360a(12) =10985a(13) =12740a(14) =14625a(15) =16640a(16) =18785a(17) =21060a(18) =23465a(19) =26000a(20) =28665a(21) =31460a(22) =34385a(23) =37440a(24) =40625a(25) =43940a(26) =47385a(27) =50960a(28) =54665a(29) =58500