a(n) = smallest nonnegative integer not the Nim sum of at most 4 earlier terms.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =31a(6) =32a(7) =64a(8) =103a(9) =128a(10) =171a(11) =213a(12) =256a(13) =301a(14) =342a(15) =439a(16) =475a(17) =494a(18) =512a(19) =558a(20) =595a(21) =911a(22) =1024a(23) =1075a(24) =1114a(25) =1189a(26) =1287a(27) =1606a(28) =1727a(29) =1996