题干
已知数列{an}的前n项和 An=n2 (n∈N* ),bn=
+
(n∈N* ) ，数列{bn}的前n项和为Bn．
| a |
| n |
| a |
| n |
| + |
| 1 |
| a |
| n |
| + |
| 1 |
| a |
| n |
