Shifts left 2 places under "BGK" (reversible, element, unlabeled) transform.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =2a(6) =4a(7) =8a(8) =12a(9) =25a(10) =43a(11) =94a(12) =177a(13) =350a(14) =702a(15) =1413a(16) =2954a(17) =5963a(18) =12333a(19) =25625a(20) =53069a(21) =111201a(22) =232727a(23) =489177a(24) =1032483a(25) =2178467a(26) =4617781a(27) =9797643a(28) =20844394a(29) =44427033