Number of polyarcs with n cells.

Terms

a(0) =2a(1) =7a(2) =22a(3) =93a(4) =364a(5) =1734a(6) =8246a(7) =41043a(8) =206602a(9) =1056831a(10) =5454954a(11) =28394727a(12) =148805868a(13) =784390909