a(n) = n*(n + 1)*(4*n - 1)/3.

Terms

a(0) =0a(1) =2a(2) =14a(3) =44a(4) =100a(5) =190a(6) =322a(7) =504a(8) =744a(9) =1050a(10) =1430a(11) =1892a(12) =2444a(13) =3094a(14) =3850a(15) =4720a(16) =5712a(17) =6834a(18) =8094a(19) =9500a(20) =11060a(21) =12782a(22) =14674a(23) =16744a(24) =19000a(25) =21450a(26) =24102a(27) =26964a(28) =30044a(29) =33350