整数的置换
{0, 1, –1, 2, –2, 3, –3, 4, –4, 5, –5, 6, –6, 7, –7, 8, –8, 9, –9, 10, –10, 11, –11, 12, –12, 13, –13, 14, –14, 15, –15, 16, –16, 17, –17, 18, –18, 19, –19, 20, –20, 21, –21, 22, –22, 23, –23, 24, –24, ...}
给出另一个双无限序列的置换(在OEIS中不允许,因为不是有序的) 给出单个无限序列的置换(在OEIS中可以接受,因为它是有序的)