Let n be a positive integer. Given a real number x, let \lfloor x\rfloor be the greatest integer less than or equal to x. For example, \lfloor 2.4\rfloor=2,\lfloor 3\rfloor=3 and \lfloor\pi\rfloor=3. Define a sequence a_{1}, a_{2}, a_{3}, \ldots where a_{1}=n and
a_{m}=\left\lfloor\frac{a_{m-1}}{3}\right\rfloor,
for all integers m \geq 2. The sequence stops when it reaches zero. The number n is said to be lucky if 0 is the only number in the sequence that is divisible by 3.
For example, 7 is lucky, since a_{1}=7, a_{2}=2, a_{3}=0, and none of 7, 2 are divisible by 3. But 10 is not lucky, since a_{1}=10, a_{2}=3, a_{3}=1, a_{4}=0, and a_{2}=3 is divisible by 3. Determine the number of lucky positive integers less than or equal to 1000.