25241364720domain: NAppears in sequencesa(n)=0!*1!*2!*3!*(4*n)!*6*n*(n-1) / ((n)!*(n+1)!*(n+2)!*(n+3)!).at n=5A181202T(n,k) = 0!*1!*2!*...*(k-1)! *(n*k)! *k*(k-1)*n*(n-1) / 2*n!*(n+1)!*...*(n+k-1)!at n=39A181204T(n,k) = 0!*1!*2!*...*(k-1)! *(n*k)! *k*(k-1)*n*(n-1) / 2*n!*(n+1)!*...*(n+k-1)!at n=41A181204