regular expression for find [# # 1] , [# # 2] ,[# # 125] .. in php

i have string 

```
"php, regu[]lar expre[# # 1]ssio [# # 2]nssadas das dasd as das dasdssd [# # 301]dfs dfsdf sd fsdfds"

```

want to replace all these with `{number}`