Need to calculate the difference between different pairs of values

Hello!

I have a column with 20 integers, from 1 to 20. Each integer is associated with a value in a second column.

These integers represent 20 evenly spaced points along a circle. Points 1 and 20 are therefore close together, whereas points 1 and 10 are maximally separated.

I need to calculate the difference between the recorded values in the second column for every possible combination of lag distances! Namely,
points with a lag distance of 1 would include (1,2) (2,3) (3,4) (4,5) ... (20,1)
points with a lag distance of 2 would include (1,3) (2,4) (3,5) (4,6) (5,7) ... (20,2)
points with a lag distance of 10 (maximal distance!) would include (1,10) (2,11) (3,12) (4,13) ... (20,10)

For each calculated difference I would also need to know which lag I'm referring to (1,2, ... 10), perhaps listed in another column.

Thank you!

Ilford