Number of forests in Moebius ladder M_n.

Terms

a(0) =0a(1) =4a(2) =38a(3) =328a(4) =2686a(5) =21224a(6) =163982a(7) =1249784a(8) =9447102a(9) =71056840a(10) =532854638a(11) =3988597144a(12) =29822927134a(13) =222836912744