Exercises 3/7 and isPalindrome

//3
public static void writeSequence(int n){//10-5 9-4 8-3 7-2
        if(n<1){
            throw new IllegalArgumentException("Value cannot be less than 1!");
        }
        if(n==1){
            System.out.print("1 ");
        }
        else if(n==2){
            System.out.print("1 1");
        }
        else {
            int r = n - n / 2;
            System.out.print(r +" ");
            writeSequence(n-2);
            System.out.print(r + " ");

        }
    }
//7
    public static void writeChars(int n){
        if(n<1){
            throw new IllegalArgumentException("Value cannot be less than 1!");
        }
        if(n==1){
            System.out.print("*");
        }
        else if(n==2){
            System.out.print("**");
        }
        else{
            System.out.print("<");
            writeChars(n-2);
            System.out.print(">");
        }
    }

//isPalindrome
 public static boolean isPalindrome(String s){
        if(s.length()<=1){
            return true;
        }
        if(s.charAt(0)==s.charAt(s.length()-1)){
            return (isPalindrome(s.substring(1,s.length()-1)));
        }
        else {
            return false;
        }
    }