294711domain: NAppears in sequencesa(n) = s(n,n) + s(n,n-1) + s(n,n-2), where s(n,k) are the unsigned Stirling numbers of the first kind (see A132393).at n=39A308305Number of subgraphs of the directed square lattice with n vertices and all vertices reachable from the origin.at n=12A353028