>>564
4, 8,  12,  16,  24…
 5, 10,  15,  20,…
□=15

(1)(1,3)(1,3,5)(1,3,5,7)(1,3,5,7,9)(1,3,5,7,9,11)…
□=3

1,   3,   5,   7,   9,  11,   13,   15,   17,   19,  … (奇数)
1/3, 1,   5/3, 7/3, 3,  11/3, 13/3,  5,  17/3, 19/3… (÷3)
1/3, 1/2, 5/9, 7/12, 3/5,11/18,13/21, 5/8, 17/27,19/30  (÷n)
□=7/12