Programming :: Multiple Input Into Seq Command From Pipe - Single Column Unique Numbers

Have this script which is reading in a series of files, one at a time with while-do-done loop, each file goes through various greps/awk's where this info is then saved to various files for later use. i.e....

Script is being run on Linux Red Hat,

In one of the grep/awk's the output (currently) are 2 columns (min max), i.e....| awk '{print $1, $2}' | sort -u which outputs (e.g.)

The number of "min max" pairs varies from file to file. Want to output a single column of unique numbers from the min max pairs & get the number of them for input to a file...i.e...

Where <PROCESS> is some process/technique that will generate a single column of integers (increment of 1) to pipe into the next one (sort -u)

i.e. (example from above)

Have tried command seq - only works for single pair input i.e.

Is there any command like seq etc which will output a single column based on a input of min max numbers (increment 1) to pipe onwards to next command?