import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class No212 {
    static int[] prime = { 2, 3, 5, 7, 11, 13 };
    static int[] composite = { 4, 6, 8, 9, 10, 12 };

    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    System.in));
            int[] a = strToIntArray(br.readLine());
            List<Integer> ansList = new ArrayList<Integer>();
            int P = a[0];
            int C = a[1];

            for (int i = 0; i < P; i++) {
                List<Integer> ansList_tmp = new ArrayList<Integer>();
                for (int j : prime) {
                    if (i == 0) {
                        ansList_tmp.add(j);
                    } else {

                        for (Integer k : ansList) {
                            ansList_tmp.add(j * k);
                        }
                    }

                }
                ansList = ansList_tmp;

            }

            for (int i = 0; i < C; i++) {
                List<Integer> ansList_tmp = new ArrayList<Integer>();
                for (int j : composite) {
                    if (P == 0 && i == 0) {
                        ansList_tmp.add(j);
                    } else {

                        for (Integer k : ansList) {
                            ansList_tmp.add(j * k);
                        }
                    }

                }
                ansList = ansList_tmp;

            }

            long sum = 0;
            for (Integer integer : ansList) {
                sum += integer;
            }

            System.out.println(sum / (double) ansList.size());
        } catch (Exception e) {
            System.err.println("Error:" + e.getMessage());
        }
    }

    static int[] strToIntArray(String S) {
        String[] strArray = S.split(" ");
        int[] intArray = new int[strArray.length];
        for (int i = 0; i < strArray.length; i++) {
            intArray[i] = Integer.parseInt(strArray[i]);
        }
        return intArray;
    }
}