n=int(input())
k=int(input())

dp=[[0]*(6*n+1) for i in range(n+1)]
dp[0][0]=1
for i in range(n):
  for j in range(6*n):
    for j2 in range(1,7):
      if j+j2<=6*n:
        dp[i+1][j+j2]+=dp[i][j]/6

dp2=[[0]*(6*n+1) for i in range(n+1)]
dp2[0][0]=1
for i in range(n):
  for j in range(6*n):
    if i<k:
      for j2 in range(4,7):
        if j+j2<=6*n:
          dp2[i+1][j+j2]+=dp2[i][j]/3
    else:
      for j2 in range(1,7):
        if j+j2<=6*n:
          dp2[i+1][j+j2]+=dp2[i][j]/6

ans=0
for i in range(6*n+1):
  for j in range(i+1,6*n+1):
    ans+=dp[-1][i]*dp2[-1][j]
print(ans)