Number of turns in all left factors of Dyck paths of length n.

Terms

a(0) =0a(1) =0a(2) =1a(3) =3a(4) =9a(5) =20a(6) =50a(7) =105a(8) =245a(9) =504a(10) =1134a(11) =2310a(12) =5082a(13) =10296a(14) =22308a(15) =45045a(16) =96525a(17) =194480a(18) =413270a(19) =831402a(20) =1755182a(21) =3527160a(22) =7407036a(23) =14872858a(24) =31097794a(25) =62403600a(26) =130007500a(27) =260757900a(28) =541574100a(29) =1085822640