How to get all the lines after a matching word till the next different matching word?

For example, my input looks like below. 

 1
 2
 3
 
 5
 6

and I need to `sed` from *1* to *5* and in my output I need to include *1* but I do not want to include *5*and the remaining lines. 

If my file contains no *5*, I need to do have the remaining lines till the end. 

I saw the referenced [link](http://unix.stackexchange.com/questions/17404/show-only-text-between-2-matching-pattern) but it doesn't answer my question.