Find the number of all ordered pairs $( a , b , c )$ of natural numbers satisfying the following conditions. [4 points] (가) $a \times b \times c$ is odd. (나) $a \leq b \leq c \leq 20$
Find the number of all ordered pairs $( a , b , c )$ of natural numbers satisfying the following conditions. [4 points]\\
(가) $a \times b \times c$ is odd.\\
(나) $a \leq b \leq c \leq 20$