a(n) = 2*n*(16*n - 13).

Terms

a(0) =0a(1) =6a(2) =76a(3) =210a(4) =408a(5) =670a(6) =996a(7) =1386a(8) =1840a(9) =2358a(10) =2940a(11) =3586a(12) =4296a(13) =5070a(14) =5908a(15) =6810a(16) =7776a(17) =8806a(18) =9900a(19) =11058a(20) =12280a(21) =13566a(22) =14916a(23) =16330a(24) =17808a(25) =19350a(26) =20956a(27) =22626a(28) =24360a(29) =26158