1+2+3+…+n |
n |
1 |
anan+1 |
1+2+3+…+n |
n |
| ||
n |
n+1 |
2 |
n+2 |
2 |
1 |
anan+1 |
1 | ||||
|
4 |
(n+1)(n+2) |
1 |
n+1 |
1 |
n+2 |
1 |
2 |
1 |
3 |
1 |
3 |
1 |
4 |
1 |
n |
1 |
n+1 |
1 |
n+1 |
1 |
n+2 |
1 |
2 |
1 |
n+2 |
2n |
n+2 |
1 |
anan+1 |
2n |
n+2 |
1 |
n(n+1) |
c1 |
b1 |
c2 |
b2 |
c3 |
b3 |
cn |
bn |
|
n |
3 |
1 |
6 |
1 |
12 |
1 |
20 |
1 |
(n+1)(n+2) |
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