On the structure of commutative rings with <i>p</i><sup><i>k</i><sub>1...</sub></sup><sub>1</sub><i>p</i><sup><i>k</i><sub><i>n</i></sub></sup><sub><i>n</i></sub>(1 &#8804; <i>k</i><sub><i>i</i></sub>  &#8804; 7) zero-divisors