Assignment:
Prove that any element σ in Sn which commutes with (1, 2 ...r) is of the form σ = (1, 2,....., r)iτ where i = 0, 1, 2,.......,r, , τ is a permutation leaving all of 1, 2 ,....r fixed.
Provide complete and step by step solution for the question and show calculations and use formulas.