Hofstadter Q-sequence: a(1) = a(2) = 1; a(n) = a(n-a(n-1)) + a(n-a(n-2)) for n > 2.

Terms

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