795872domain: NAppears in sequencesa(n) = gcd(n!, binomial(2n,n)).at n=31A135322a(n) = binomial(2*n, n) / Product(p prime | n < p <= 2*n).at n=31A263931a(n) = binomial(2*n-4,n-1)*(n+3)/n.at n=12A271823