191178domain: NAppears in sequencesE.g.f.: 1 / (1 - x * exp(3*x)).at n=6A336951Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = n! * Sum_{j=0..n} (k * (n-j))^j/j!.at n=51A351790a(n) = Sum_{k=0..floor(2*n/3)} binomial(k+2,2) * binomial(k,2*n-3*k).at n=22A392269