Number of subgraphs of the directed square lattice with n vertices and all vertices reachable from the origin.

A353028

Number of subgraphs of the directed square lattice with n vertices and all vertices reachable from the origin.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =5a(4) =15a(5) =47a(6) =156a(7) =527a(8) =1826a(9) =6407a(10) =22762a(11) =81587a(12) =294711a(13) =1070973a(14) =3912808a(15) =14358493a(16) =52893647a(17) =195498831a(18) =724704974a(19) =2693397035a(20) =10033263089a(21) =37452388361a(22) =140063288728

External references