Question

1, 9, 35, 91, 189, ( ) A.301 B.321 C.341 D.361 请高手解答一下。谢谢。

Answer 1

----------------
1*1
3*3
5*7
7*13
9*21
11*31=341
1,3,7,13,21,31
2,4,6,8,10
答案是C

Answer 2

选c、341
此为三级等差数列，后一项减前一项
1 9 35 91 189 (341)
\ / \ / \ / \ / \ /
8 26 56 98 (152)
\ / \ / \ / \ /
18 30 42 (54)
\ / \ / \ /
12 12 (12)

Answer 3

1*1 = 1* (1*0+1)
3*3 = 3* (1*2+1)
5*7 = 5* (2*3+1)
7*13 = 7 * (3*4+1)
9*21 = 9 * (4*5+1)
11*31 = 11 * (5*6+1)
……

第N个数 = (2N-1)×[ N(N-1)+1] = (2N-1)×( N²-N+1)