Number of spanning trees with degrees 1 and 3 in D_4 X P_n.

Terms

a(0) =1a(1) =4a(2) =16a(3) =92a(4) =432a(5) =1884a(6) =8582a(7) =39736a(8) =181936a(9) =829672a(10) =3793850a(11) =17366388a(12) =79441576a(13) =363298928a(14) =1661695126a(15) =7601017276a(16) =34767611570a(17) =159026305464a(18) =727389859704