I want to add, and it is not clear from my example, that the values are not
sorted, however, all the entries with the same value are together, i.e. the
column can look like this:

1
1
1
3
3
3
....
45
45
2
2
....
"petermcwerner" wrote:

I have a column with transaction numbers which are non unique values, but
some values are missing

1
1
2
2
2
4
4
5
5
6
6
6
8
8
....
10000

I want to output a list of the missing values:
3
7
....