3351040domain: NAppears in sequencesa(n) = n-th sextic factorial number divided by 4.at n=5A0347244-parking triangle T(r, i, 4) read by rows: T(r, i, k) = (r + 1)^(i-1)*binomial(k*(r + 1) + r - i - 1, r - i) with k = 4 and 0 <= i <= r.at n=31A329060