Number of UDL's in all skew Dyck paths of semilength n.

Terms

a(0) =0a(1) =0a(2) =1a(3) =4a(4) =16a(5) =68a(6) =301a(7) =1366a(8) =6301a(9) =29400a(10) =138355a(11) =655424a(12) =3121438a(13) =14930540a(14) =71675839a(15) =345148892a(16) =1666432816a(17) =8064278288a(18) =39103576699a(19) =189949958332a(20) =924163714216