A045625 Number of n-bead black-white reversible strings with fundamental period n.

1, 2, 1, 4, 7, 18, 29, 70, 126, 266, 507, 1054, 2037, 4158, 8183, 16488, 32760, 65790, 131026, 262654, 524265, 1049524, 2097119, 4196350, 8388450, 16781292, 33554367, 67116784, 134217657, 268451838, 536870247, 1073774590, 2147483520