a(n) = Sum_{k=0..n} binomial(4*n+2,k) * binomial(4*n-k-1,n-k).

A386837

a(n) = Sum_{k=0..n} binomial(4*n+2,k) * binomial(4*n-k-1,n-k).

Terms

    a(0) =1a(1) =9a(2) =126a(3) =1978a(4) =32703a(5) =556887a(6) =9665476a(7) =170006256a(8) =3019802253a(9) =54047520709a(10) =973141183002

External references