An upper bound for linearized chord diagrams.

Terms

a(0) =1a(1) =2a(2) =3a(3) =6a(4) =11a(5) =29a(6) =90a(7) =447a(8) =2777a(9) =21492a(10) =189275a(11) =1875602a(12) =20491475a(13) =244801738a(14) =3171481173a(15) =44283667569a(16) =662856700938