"DIK" (bracelet, indistinct, unlabeled) transform of A000237.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =14a(5) =43a(6) =143a(7) =496a(8) =1794a(9) =6667a(10) =25345a(11) =98032a(12) =384713a(13) =1527480a(14) =6125327a(15) =24770186a(16) =100897860a(17) =413595904a(18) =1704840125a(19) =7062024986a(20) =29382224119a(21) =122731488819a(22) =514491387498