Number of irreducible systems of meanders.

Terms

a(0) =1a(1) =1a(2) =2a(3) =8a(4) =46a(5) =322a(6) =2546a(7) =21870a(8) =199494a(9) =1904624a(10) =18846714a(11) =191955370a(12) =2002141126a(13) =21303422480a(14) =230553207346