___________________________________________
 110 = 8 * 13 + 4 *  1 + 2 *  1 + 1 *  0
___________________________________________
 111 = 8 * 13 + 4 *  1 + 2 *  1 + 1 *  1
___________________________________________
 112 = 8 * 14 + 4 *  0 + 2 *  0 + 1 *  0
___________________________________________
 113 = 8 * 14 + 4 *  0 + 2 *  0 + 1 *  1
___________________________________________
 114 = 8 * 14 + 4 *  0 + 2 *  1 + 1 *  0
___________________________________________
 115 = 8 * 14 + 4 *  0 + 2 *  1 + 1 *  1
___________________________________________
 116 = 8 * 14 + 4 *  1 + 2 *  0 + 1 *  0
___________________________________________
 117 = 8 * 14 + 4 *  1 + 2 *  0 + 1 *  1
___________________________________________
 118 = 8 * 14 + 4 *  1 + 2 *  1 + 1 *  0
___________________________________________
 119 = 8 * 14 + 4 *  1 + 2 *  1 + 1 *  1
___________________________________________
 120 = 8 * 15 + 4 *  0 + 2 *  0 + 1 *  0
___________________________________________
 121 = 8 * 15 + 4 *  0 + 2 *  0 + 1 *  1
___________________________________________
 122 = 8 * 15 + 4 *  0 + 2 *  1 + 1 *  0
___________________________________________
 123 = 8 * 15 + 4 *  0 + 2 *  1 + 1 *  1
___________________________________________
 124 = 8 * 15 + 4 *  1 + 2 *  0 + 1 *  0
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任何一个自然数都可以分解成8421的表达式