a(n) = (4*n)! / (n!^4 * (n+1)).A207817a(n) = (4*n)! / (n!^4 * (n+1)).Terms a(0) =1a(1) =12a(2) =840a(3) =92400a(4) =12612600a(5) =1955457504a(6) =329820499008External referencesoeis: A207817