DIK(b)-DIK[ 2 ](b)-b where b is A035082.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =2a(6) =3a(7) =7a(8) =14a(9) =33a(10) =74a(11) =180a(12) =438a(13) =1090a(14) =2741a(15) =6994a(16) =17966a(17) =46565a(18) =121440a(19) =318597a(20) =839953a(21) =2224486a(22) =5914248a(23) =15780662a(24) =42241422a(25) =113402369a(26) =305254039a(27) =823690961a(28) =2227640597a(29) =6037142355