E.g.f.: -LambertW(-arcsin(x)).

Terms

a(0) =0a(1) =1a(2) =2a(3) =10a(4) =72a(5) =724a(6) =9184a(7) =142080a(8) =2587392a(9) =54290256a(10) =1289277440a(11) =34191270752