M, N = map(int, input().split())

a = {M:1}
for i in range(N):
    b = {}
    for k in a:
        b.setdefault(k * 2, 0)
        b[k * 2] += a[k]
        b.setdefault(k + 1, 0)
        b[k + 1] += a[k]
        b.setdefault(0, 0)
        b[0] += a[k]
    a = b
print(sum(k * a[k] for k in a) / (3 ** N))