Zhang Changcai. A SUFFICIENT CONDITION OF TWOFOLD MAGIC SQUARE[J]. Journal of Civil and Environmental Engineering, 1993, 15(4). DOI: 10.11835/j.issn.1674-4764.1993.04.019.
This paper uses n nature numbers from 1 to n to form a numerical table of twofold maoic square' s necessary condition. It also proves that x>n(n-1) and the numerical table is the sufficient condition of the basic solution.