The permutation f = (1,4,2) takes 1 to 4, then 4 to 2, and 2 to 1
(The reason it takes 2 to 1 is because the last number in
a cycle is considered to go to the first number)
Its inverse is what takes each back to what it was before.
So the inverse takes 4 back to 1, 1 back to 2, and 2 back to 4.
f-1 = (4,1,2) which is the same as (1,2,4)
Edwin