表格开始：
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, ...
8, 7, 4, 0, 0, 0, 0, 0, 0, 0, 0, ...
19, 17, 14, 8, 0, 0, 0, 0, 0, 0, 0, ...
43, 39, 37, 28, 16, 0, 0, 0, 0, 0, 0, ...
94, 88, 83, 74, 56, 32, 0, 0, 0, 0, 0, ...
201, 192, 181, 175, 148, 112, 64, 0, 0, 0, 0, ...
423, 408, 387, 377, 350, 296, 224, 128, 0, 0, 0, ...
880, 855, 824, 799, 781, 700, 592, 448, 256, 0, 0, ...
......................................................
a（3,1）是包含两个差值为2的元素的{1,2,3}的子集数。其中有两个：{1,3}和{1,2,3}，所以a（1,3）=2。
