150, Answer 21

來源: 於 2010-07-16 12:59:28 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

150 2, 4, 7, 12, ?, 38

2 X 2 - 0 = 4
2 X 4 - 1 = 7
2 X 7 - 2 = 12
2 X 12 - 3 = 21
2 X 21 - 4 = 38