How do I reunite those if conditions in one loop?

i've been trying to loop these if but i don't get it, where do I have to put the loop?

public static void Run(int n) {
        int l;
        int c;
        for (l = 1; l <= 2 * n - 1; l++) {
            System.out.println("\n");
            for (c = 1; c <= 2 * n - 1; c++) {

                if ((l == 1) || (l == 2 * n - 1) || (c == 1) || (c == 2 * n - 1)) {
                    System.out.print('a');
                } else if ((l == 2) || (l == 2 * n - 2) || (c == 2) || (c == 2 * n - 2)) {
                    System.out.print(defLettre(n, 1));
                } else if ((l == 3) || (l == 2 * n - 3) || (c == 3) || (c == 2 * n - 3)) {
                    System.out.print(defLettre(n, 2));
                } else if ((l == 4) || (l == 2 * n - 4) || (c == 4) || (c == 2 * n - 4)) {
                    System.out.print(defLettre(n, 3));
                } else if ((l == 5) || (l == 2 * n - 5) || (c == 5) || (c == 2 * n - 5)) {
                    System.out.print(defLettre(n, 4));

                } else {
                    System.out.print(" ");
                }

            }

        }

    }
}

Thing is, the more n becomes the more if I have to input and i don't get how you reunite them.

Thanks for your help