Number of closed walks of length n at a vertex of the cyclic graph on 9 nodes C_9.

Terms

a(0) =1a(1) =0a(2) =2a(3) =0a(4) =6a(5) =0a(6) =20a(7) =0a(8) =70a(9) =2a(10) =252a(11) =22a(12) =924a(13) =156a(14) =3432a(15) =910a(16) =12870a(17) =4760a(18) =48622a(19) =23256a(20) =184796a(21) =108528a(22) =705894a(23) =490314a(24) =2708204a(25) =2163150a(26) =10430500a(27) =9373652a(28) =40313160a(29) =40060078