a(n) = binomial(Catalan(n), 4).

A119549

a(n) = binomial(Catalan(n), 4).

Terms

    a(0) =0a(1) =0a(2) =0a(3) =5a(4) =1001a(5) =111930a(6) =12082785a(7) =1391641251a(8) =173503885555

External references