Palindromic Substrings

Aniket is obsessed with strings. One day he wondered how many strings of length N exist whose every K length substring is a palindrome. Of course, such strings depend on the number of letters of the language of strings(like English language has 26 letters). He is interested in finding the sum of number of strings for the languages having L,L+1.... R letters. Since Aniket has to go Mumbai this week