1 |
4 |
1 |
sn |
1 |
4 |
1 |
4 |
1 |
4 |
1 |
4 |
a | 2n |
a | 2n-1 |
1 |
Sn |
1 |
2 |
1 |
n |
1 |
n+2 |
1 |
2 |
1 |
3 |
1 |
2 |
1 |
4 |
1 |
n-1 |
1 |
n+1 |
1 |
n |
1 |
n+2 |
1 |
2 |
3 |
2 |
2n+3 |
(n+1)(n+2) |
3 |
4 |
2n+3 |
2(n+1)(n+2) |
1 |
a1 |
1 |
a2 |
1 |
an |
1 |
3 |
1 |
3 |
1 |
3 |
1 |
1×4 |
1 |
4×7 |
1 |
7×10 |
1 |
(3n-2)(3n+1) |
A.
| B.
| C.
| D.
|
1 |
anan=1 |
1 |
2 |
© 2017-2019 超级试练试题库,All Rights Reserved.