"BHK" (reversible, identity, unlabeled) transform of 1,2,3,4,...

Terms

a(0) =1a(1) =2a(2) =5a(3) =10a(4) =27a(5) =66a(6) =181a(7) =470a(8) =1263a(9) =3310a(10) =8767a(11) =22980a(12) =60449a(13) =158354a(14) =415353a(15) =1087690a(16) =2849675a(17) =7461318a(18) =19539429a(19) =51156950a(20) =133944931a(21) =350677822a(22) =918123935a(23) =2403693960a(24) =6293050657a(25) =16475457986a(26) =43133566061