I want to replace text files using sed but with a sequence.

example.txt：

```
1. 2000000
2. 2000000
3. 2000000
4. 2000000

```

I want a result like：

```
1. 2000000
2. 1900000
3. 1800000
4. 1700000

```

I have this dirty way:

```
for i in {2000000..1700000..-100000}; do sed -i -e "0,/2000000/! {0,/2000000/ s/2000000/$i/}" example.txt; done

```

Any better idea?