Number of (undirected) Hamiltonian cycles in the n-antiprism graph.

Terms

a(0) =3a(1) =9a(2) =16a(3) =29a(4) =56a(5) =110a(6) =225a(7) =469a(8) =991a(9) =2110a(10) =4511a(11) =9666a(12) =20736a(13) =44511a(14) =95575a(15) =205253a(16) =440828a(17) =946817a(18) =2033628a(19) =4367986a(20) =9381949a(21) =20151433a(22) =43283195a(23) =92967882a(24) =199685571a(25) =428904390a(26) =921243268a(27) =1978737467a(28) =4250128235a(29) =9128846273