Triangle giving numbers of closed plane meanders.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =6a(5) =1a(6) =1a(7) =20a(8) =20a(9) =1a(10) =1a(11) =50a(12) =160a(13) =50a(14) =1a(15) =1a(16) =105a(17) =808a(18) =808a(19) =105a(20) =1a(21) =1a(22) =196a(23) =3066a(24) =7294a(25) =3066a(26) =196a(27) =1a(28) =1a(29) =336