1 |
n+1 |
1 |
n+2 |
1 |
2n+1 |
an+1=
1 |
n+2 |
1 |
n+3 |
1 |
2n+3 |
an+1-an=
1 |
2n+2 |
1 |
2n+3 |
1 |
n+1 |
所以{an}对于n为正整数时为单调递减数列,
使不等式
1 |
n+1 |
1 |
n+2 |
1 |
2n+1 |
1 |
3 |
就是n=1时,a>2007
1 |
3 |
1 |
2 |
1 |
3 |
1 |
6 |
故答案为:2009.
1 |
n+1 |
1 |
n+2 |
1 |
2n+1 |
1 |
3 |
1 |
n+1 |
1 |
n+2 |
1 |
2n+1 |
1 |
n+2 |
1 |
n+3 |
1 |
2n+3 |
1 |
2n+2 |
1 |
2n+3 |
1 |
n+1 |
1 |
n+1 |
1 |
n+2 |
1 |
2n+1 |
1 |
3 |
1 |
3 |
1 |
2 |
1 |
3 |
1 |
6 |