NEW : Probation report recommends 18 years ; defense asks for six . O.J . is found not guilty of murder in the death of his wife Nicole Brown Simpson, but convicted on a lesser charge of armed robbery and sentenced to serve only 6 1/2 years. Judge to sentence Simpson on Friday in Las Vegas sports memorabilia case .
NEW : Probation report recommends 18 years ; defense asks for six . O.J . Simpson convicted of robbery , kidnapping in October . Judge to sentence Simpson on Friday in Las Vegas sports memorabilia case .