N = int(input())
K = int(input())
dp = [[[0] * 2 for j in range(61)] for i in range(N + 1)]
dp[0][0][0] = 1
dp[0][0][1] = 1
for i in range(1, N + 1):
    if i <= K:
        for deme in range(4, 7):
            for j in range(61):
                if j + deme <= 60:
                    dp[i][j + deme][0] += dp[i - 1][j][0] / 3
    else:
        for deme in range(1, 7):
            for j in range(61):
                if j + deme <= 60:
                    dp[i][j + deme][0] += dp[i - 1][j][0] / 6
    for deme in range(1, 7):
        for j in range(61):
            if j + deme <= 60:
                dp[i][j + deme][1] += dp[i - 1][j][1] / 6
ans = 0
for i in range(61):
    for j in range(i + 1, 61):
        ans += dp[-1][j][0] * dp[-1][i][1]
print(ans)