a(n) = Sum_{i=1..n} binomial(6*i,3*i).

A066798

a(n) = Sum_{i=1..n} binomial(6*i,3*i).

Terms

    a(0) =20a(1) =944a(2) =49564a(3) =2753720a(4) =157871240a(5) =9233006540a(6) =547490880980

External references