Number of Hamiltonian cycles in C_4 X C_n.

Terms

a(0) =126a(1) =1344a(2) =2930a(3) =28060a(4) =55230a(5) =538744a(6) =969378a(7) =10066228a(8) =16284862a(9) =186362560a(10) =265582226a(11) =3447630284a(12) =4238980734a(13) =64031790664a(14) =66561185858