Shifts left 2 places under COMPOSE transform.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =10a(6) =28a(7) =86a(8) =286a(9) =1019a(10) =3857a(11) =15418a(12) =64782a(13) =285041a(14) =1309355a(15) =6263085a(16) =31127475a(17) =160432093a(18) =856039863a(19) =4721638083a(20) =26883787141a(21) =157812750656a(22) =953995201996