a(n) = -n^2 - n + 72.

Terms

a(0) =72a(1) =70a(2) =66a(3) =60a(4) =52a(5) =42a(6) =30a(7) =16a(8) =0a(9) =-18a(10) =-38a(11) =-60a(12) =-84a(13) =-110a(14) =-138a(15) =-168a(16) =-200a(17) =-234a(18) =-270a(19) =-308a(20) =-348a(21) =-390a(22) =-434a(23) =-480a(24) =-528a(25) =-578a(26) =-630a(27) =-684a(28) =-740a(29) =-798