a(n) = (6*n+1)!/(n!*(2*n)!*(3*n+1)!).A368513a(n) = (6*n+1)!/(n!*(2*n)!*(3*n+1)!).Terms a(0) =1a(1) =105a(2) =25740a(3) =7759752a(4) =2574148500a(5) =902522205585External referencesoeis: A368513