1 |
a1 |
1 |
a2 |
1 |
a3 |
1 |
a2011 |
A.
| B.
| C.
| D.
|
n(n+1) |
2 |
1 |
an |
2 |
n(n+1) |
1 |
n |
1 |
n+1 |
1 |
a1 |
1 |
a2 |
1 |
an |
1 |
2 |
1 |
3 |
1 |
4 |
1 |
n |
1 |
n+1 |
1 |
n+1 |
2n |
n+1 |
1 |
a1 |
1 |
a2 |
1 |
a2011 |
2×2011 |
2012 |
2011 |
1006 |
an+1 |
2 |
1 |
anan+1 |
1 |
n(n+1) |
1 |
bn |
n+1 |
n |
A.10 | B.11 | C.120 | D.121 |
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