3123632domain: NAppears in sequencesTriangle read by rows, T(n,k) = Sum_{j=0..n} (-1)^(n-j)*C(-j,-n)*L(j,k), L the unsigned Lah numbers A271703, for n>=0 and 0<=k<=n.at n=47A271704Number of sequences of balls colored with at most n colors such that exactly one ball is of a color seen earlier in the sequence.at n=7A281912