Problem 76
Counting summations
It is possible to write five as a sum in exactly six different ways:
$$
\begin{aligned}
&4 + 1\\
&3 + 2\\
&3 + 1 + 1\\
&2 + 2 + 1\\
&2 + 1 + 1 + 1\\
&1 + 1 + 1 + 1 + 1
\end{aligned}
$$
How many different ways can one hundred be written as a sum of at least two positive integers?
加和计数
将$5$写成至少两个正整数的和,有$6$种不同的方式:
$$
\begin{aligned}
&4 + 1\\
&3 + 2\\
&3 + 1 + 1\\
&2 + 2 + 1\\
&2 + 1 + 1 + 1\\
&1 + 1 + 1 + 1 + 1
\end{aligned}
$$
将$100$写成至少两个正整数的和,有多少种不同的方式?