a(n) = 4*n^3 - 6*n^2 + 3*n - 1.

Terms

a(0) =0a(1) =13a(2) =62a(3) =171a(4) =364a(5) =665a(6) =1098a(7) =1687a(8) =2456a(9) =3429a(10) =4630a(11) =6083a(12) =7812a(13) =9841a(14) =12194a(15) =14895a(16) =17968a(17) =21437a(18) =25326a(19) =29659a(20) =34460a(21) =39753a(22) =45562a(23) =51911a(24) =58824a(25) =66325a(26) =74438a(27) =83187a(28) =92596a(29) =102689