Number of semi-meanders of order n with 5 components.

Terms

a(0) =1a(1) =5a(2) =24a(3) =104a(4) =438a(5) =1796a(6) =7238a(7) =28848a(8) =113518a(9) =444278a(10) =1720384a(11) =6643492a(12) =25421620a(13) =97136712a(14) =368280210a(15) =1395104236a(16) =5250325378a(17) =19746342212a(18) =73863421894a(19) =276113486146