1471680domain: NAppears in sequencesNumber of 2-divided words of length n over a 3-letter alphabet.at n=12A210323Triangle read by rows: T(n, k) = (Sum_{i=0..n-k} (-1)^i * binomial(n-k, i) * (n+2-i)!) * binomial(n, k) / ((k+1) * (k+2)) for 0 <= k <= n.at n=42A373050