How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10?
How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10 ?
$$\small{\text{
$
\begin{array}{r|rcl|r}
\hline
n & p_1 & & p_2 & p_1\cdot p_2 \\
\hline
1 & 11 & \cdot & 13 & = 143 \\
2 & 11 & \cdot & 17 & = 187 \\
3 & 11 & \cdot & 19 & = 209 \\
4 & 11 & \cdot & 23 & = 253 \\
5 & 11 & \cdot & 29 & = 319 \\
6 & 11 & \cdot & 31 & = 341 \\
7 & 11 & \cdot & 37 & = 407 \\
8 & 11 & \cdot & 41& = 451 \\
9 & 11 & \cdot & 43 & = 473 \\
10 & 13 & \cdot & 17 & = 221 \\
11 & 13 & \cdot & 19 & = 247 \\
12 & 13 & \cdot & 23 & = 299 \\
13 & 13 & \cdot & 29& = 377 \\
14 & 13 & \cdot & 31 & = 403 \\
15 & 13 & \cdot & 37 & = 481 \\
16 & 17 & \cdot & 19 & = 323 \\
17 & 17 & \cdot & 23 & = 391 \\
18 & 17 & \cdot & 29 & = 493 \\
19 & 19 & \cdot & 23 & = 437 \\
\hline
\end{array}
$
}}$$
How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10 ?
$$\small{\text{
$
\begin{array}{r|rcl|r}
\hline
n & p_1 & & p_2 & p_1\cdot p_2 \\
\hline
1 & 11 & \cdot & 13 & = 143 \\
2 & 11 & \cdot & 17 & = 187 \\
3 & 11 & \cdot & 19 & = 209 \\
4 & 11 & \cdot & 23 & = 253 \\
5 & 11 & \cdot & 29 & = 319 \\
6 & 11 & \cdot & 31 & = 341 \\
7 & 11 & \cdot & 37 & = 407 \\
8 & 11 & \cdot & 41& = 451 \\
9 & 11 & \cdot & 43 & = 473 \\
10 & 13 & \cdot & 17 & = 221 \\
11 & 13 & \cdot & 19 & = 247 \\
12 & 13 & \cdot & 23 & = 299 \\
13 & 13 & \cdot & 29& = 377 \\
14 & 13 & \cdot & 31 & = 403 \\
15 & 13 & \cdot & 37 & = 481 \\
16 & 17 & \cdot & 19 & = 323 \\
17 & 17 & \cdot & 23 & = 391 \\
18 & 17 & \cdot & 29 & = 493 \\
19 & 19 & \cdot & 23 & = 437 \\
\hline
\end{array}
$
}}$$