For length 1 string w = a
(a^{R})(a^{R})...(for k times)=(aa...(for k times))^{R}
For length 2 string w = ab
(ab^{R})(ab^{R})...(for k times)=(abab...(for k times))^{R}
babababababab..ba = babababababa..ba
so for string for length k
(w^{R})(w^{R})...(for k times)=(ww...(for k times))^{R}