import itertools

N = int(input())
K = int(input())

TARO = [0]*(N*6+2)
ZIRO = [0]*(N*6+2)
TARO[0]=1
for i in range(K):
    NTARO=[0]*(N*6+2)
    for j in range(N*6+2):
        if TARO[j]>0:
            NTARO[j+4] += TARO[j]/3
            NTARO[j+5] += TARO[j]/3
            NTARO[j+6] += TARO[j]/3
    TARO = NTARO
for i in range(N-K):
    NTARO=[0]*(N*6+2)
    for j in range(N*6+2):
        if TARO[j]>0:
            NTARO[j+1] += TARO[j]/6
            NTARO[j+2] += TARO[j]/6
            NTARO[j+3] += TARO[j]/6
            NTARO[j+4] += TARO[j]/6
            NTARO[j+5] += TARO[j]/6
            NTARO[j+6] += TARO[j]/6
    TARO = NTARO
ZIRO[0]=1
for i in range(N):
    NZIRO=[0]*(N*6+2)
    for j in range(N*6+2):
        if ZIRO[j]>0:
            NZIRO[j+1] += ZIRO[j]/6
            NZIRO[j+2] += ZIRO[j]/6
            NZIRO[j+3] += ZIRO[j]/6
            NZIRO[j+4] += ZIRO[j]/6
            NZIRO[j+5] += ZIRO[j]/6
            NZIRO[j+6] += ZIRO[j]/6
    ZIRO = NZIRO

ZIROAC = list(itertools.accumulate(ZIRO))
ans = 0
for i in range(N*6+2):
    ans += TARO[i]*(ZIROAC[i-1])
print(ans)