Catafusenes (see reference for precise definition).

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =37a(5) =149a(6) =630a(7) =2713a(8) =11899a(9) =52789a(10) =236345a(11) =1066317a(12) =4842531a(13) =22117897a(14) =101535659a(15) =468233674a(16) =2168094625a(17) =10076216851a(18) =46986691678a(19) =219777820957