29966636700domain: NAppears in sequencesa(n) = (20*n)!*(6*n)!*n!/((12*n)!*(10*n)!*(3*n)!*(2*n)!).at n=2A295470a(n) = (10*n)!*(3*n)!*(n/2)!/((6*n)!*(5*n)!*(3*n/2)!*n!).at n=4A364178