a(n) = n-40.

Terms

a(0) =-40a(1) =-39a(2) =-38a(3) =-37a(4) =-36a(5) =-35a(6) =-34a(7) =-33a(8) =-32a(9) =-31a(10) =-30a(11) =-29a(12) =-28a(13) =-27a(14) =-26a(15) =-25a(16) =-24a(17) =-23a(18) =-22a(19) =-21a(20) =-20a(21) =-19a(22) =-18a(23) =-17a(24) =-16a(25) =-15a(26) =-14a(27) =-13a(28) =-12a(29) =-11