a(n) = n*(15*n-11)/2.

Terms

a(0) =0a(1) =2a(2) =19a(3) =51a(4) =98a(5) =160a(6) =237a(7) =329a(8) =436a(9) =558a(10) =695a(11) =847a(12) =1014a(13) =1196a(14) =1393a(15) =1605a(16) =1832a(17) =2074a(18) =2331a(19) =2603a(20) =2890a(21) =3192a(22) =3509a(23) =3841a(24) =4188a(25) =4550a(26) =4927a(27) =5319a(28) =5726a(29) =6148