Number of graceful labelings of the n-cycle graph.

Terms

a(0) =12a(1) =16a(2) =0a(3) =0a(4) =168a(5) =384a(6) =0a(7) =0a(8) =4576a(9) =11808a(10) =0a(11) =0a(12) =232920a(13) =654848a(14) =0a(15) =0a(16) =16141792a(17) =48181600a(18) =0a(19) =0a(20) =1540635588a(21) =5155171200a(22) =0a(23) =0