Maybe something like this?

Formula: copy to clipboard 
="XO"&TEXT(ROWS(A$1:A1000),"0000-1")


Data Range
A
1
XO1000-1
2
XO1001-1
3
XO1002-1
4
XO1003-1
5
XO1004-1
6
XO1005-1
7
XO1006-1
8
XO1007-1
9
XO1008-1
10
XO1009-1