Nimsum n + 9.

Terms

a(0) =9a(1) =8a(2) =11a(3) =10a(4) =13a(5) =12a(6) =15a(7) =14a(8) =1a(9) =0a(10) =3a(11) =2a(12) =5a(13) =4a(14) =7a(15) =6a(16) =25a(17) =24a(18) =27a(19) =26a(20) =29a(21) =28a(22) =31a(23) =30a(24) =17a(25) =16a(26) =19a(27) =18a(28) =21a(29) =20