a(n) = n^3 + 3*n + 1.

Terms

a(0) =1a(1) =5a(2) =15a(3) =37a(4) =77a(5) =141a(6) =235a(7) =365a(8) =537a(9) =757a(10) =1031a(11) =1365a(12) =1765a(13) =2237a(14) =2787a(15) =3421a(16) =4145a(17) =4965a(18) =5887a(19) =6917a(20) =8061a(21) =9325a(22) =10715a(23) =12237a(24) =13897a(25) =15701a(26) =17655a(27) =19765a(28) =22037a(29) =24477