a(1) = a(2) = 1, a(n) = n - a(a(n-1)) - a(a(n-2)).

Terms

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