a(n) = binomial(2*n,n)^4/(n + 1)^2.A186418a(n) = binomial(2*n,n)^4/(n + 1)^2.Terms a(0) =1a(1) =4a(2) =144a(3) =10000a(4) =960400a(5) =112021056a(6) =14876193024External referencesoeis: A186418