Number of 8-cycles in the hypercube graph Q_n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =6a(4) =696a(5) =6720a(6) =39840a(7) =184800a(8) =736512a(9) =2644992a(10) =8801280a(11) =27624960a(12) =82790400a(13) =238977024a(14) =668688384a(15) =1822679040a(16) =4858183680a(17) =12700876800a(18) =32647938048a(19) =82682707968a(20) =206650736640a(21) =510425825280