There is exactly one Z2Z4-cyclic 1-perfect code

Let C be a Z2Z4-additive code of length n > 3. We prove that if the binary Gray image of C, C = Φ(C), is a 1-perfect nonlinear code, then C cannot be a Z2Z4-cyclic code except for one case of length n = 15. Moreover, we give a parity check matrix for this cyclic code. Adding an even parity check coordinate to a Z2Z4-additive 1-perfect code gives an extended 1-perfect code. We also prove that any such code cannot be Z2Z4-cyclic.