Number of multi-directed animals with n vertices.

Terms

a(0) =1a(1) =4a(2) =20a(3) =110a(4) =636a(5) =3790a(6) =23036a(7) =141946a(8) =883360a(9) =5538098a(10) =34917224a(11) =221125102a(12) =1405276324a(13) =8956020294a(14) =57209977908a(15) =366147270370