a(n) = n*(8*n+3).

Terms

a(0) =0a(1) =11a(2) =38a(3) =81a(4) =140a(5) =215a(6) =306a(7) =413a(8) =536a(9) =675a(10) =830a(11) =1001a(12) =1188a(13) =1391a(14) =1610a(15) =1845a(16) =2096a(17) =2363a(18) =2646a(19) =2945a(20) =3260a(21) =3591a(22) =3938a(23) =4301a(24) =4680a(25) =5075a(26) =5486a(27) =5913a(28) =6356a(29) =6815