public static void main(String args[]){
        CountAs ca =new CountAs();
        System.out.println(ca.countAsRec(25));
        System.out.println(ca.countAs(25));
              
    }
http://www.geeksforgeeks.org/how-to-print-maximum-number-of-a-using-given-four-keys/
Test cases
Negative number
Number less than 7
Number greater than equal to 7
src/com/interview/dynamic/CountAs.java