an |
2n |
a7-a2 |
7-2 |
-5-0 |
5 |
n(n-1) |
2 |
an |
2n |
2-n |
2n |
1 |
2 |
1 |
22 |
1 |
23 |
1 |
2n |
1 |
2 |
1 |
22 |
1 |
23 |
1 |
24 |
1 |
2n+1 |
1 |
2 |
1 |
2 |
1 |
4 |
1 |
8 |
1 |
16 |
1 |
2n |
1 |
2n+1 |
1 |
2 |
1 |
4 |
1 |
8 |
1 |
2n |
1 |
2n+1 |
| ||||
1-
|
1 |
2n+1 |
1 |
2n |
1 |
2n+1 |
1 |
2n+1 |
n |
2n |
A.10 | B.9 | C.8 | D.7 |
1 |
9 |
4 |
9 |
1 |
2 |
an |
2n |
A.50 | B.51 | C.50或51 | D.51或52 |
1 |
an2-1 |
1 |
8 |
1 |
4 |
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