1641. Count Sorted Vowel Strings

class Solution {
    public int countVowelStrings(int n) {
        int a = 1 , e = 1 , o = 1, u = 1, i =1;
        for(int k = 1 ; k < n ; k++){
            a = a+e+i+o+u;
            e = e+i+o+u;
            i = i+o+u;
            o = o+u;
        }
        return a+e+i+o+u;
    }
}