Number of walks of length n on P_3 plus a loop at the end.

Terms

a(0) =1a(1) =0a(2) =1a(3) =0a(4) =2a(5) =1a(6) =5a(7) =5a(8) =14a(9) =19a(10) =42a(11) =66a(12) =131a(13) =221a(14) =417a(15) =728a(16) =1341a(17) =2380a(18) =4334a(19) =7753a(20) =14041a(21) =25213a(22) =45542a(23) =81927a(24) =147798a(25) =266110a(26) =479779a(27) =864201a(28) =1557649a(29) =2806272