The number of primes that are divisible by 9

The number of primes that are divisible by 19

The number of prime factors of n

The number of prime factors of $$\frac{n}{2}$$

b

8

The number of 3-digit integers all of whose digits are even

The number of 3-digit integers all of whose digits are odd

x

y

$$-\frac{1}{2}$$

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44本权威书籍