a(n) = 40-n.

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