a(n) = 4*n^3 + 4.

Terms

a(0) =4a(1) =8a(2) =36a(3) =112a(4) =260a(5) =504a(6) =868a(7) =1376a(8) =2052a(9) =2920a(10) =4004a(11) =5328a(12) =6916a(13) =8792a(14) =10980a(15) =13504a(16) =16388a(17) =19656a(18) =23332a(19) =27440a(20) =32004a(21) =37048a(22) =42596a(23) =48672a(24) =55300a(25) =62504a(26) =70308a(27) =78736a(28) =87812a(29) =97560