n |
n+1 |
1 |
an |
n |
n+1 |
1 |
2 |
n |
n+1 |
n-1 |
n |
n2-(n2-1) |
n(n+1) |
1 |
n(n+1) |
1 |
2 |
1 |
n(n+1) |
1 |
n(n+1) |
1 |
n(n+1) |
1 |
an |
1 |
an |
1 |
a1 |
1 |
a2 |
1 |
an |
n(n+1) |
2 |
n(n+1)(2n+1) |
6 |
n(n+1)(n+2) |
3 |
1 |
an |
n(n+1)(n+2) |
3 |
2 |
3 |
A.4 | B.6 | C.8 | D.10 |
A.18 | B.27 | C.36 | D.9 |
1 |
S1 |
1 |
S2 |
1 |
S3 |
1 |
S2006 |
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