何かを書き留める何か

数学や読んだ本について書く何かです。最近は社会人として生き残りの術を学ぶ日々です。

2013-06-10から1日間の記事一覧

Project Euler Problem 21

Let $d(n)$ be defined as the sum of proper divisors of $n$ (numbers less than $n$ which divide evenly into $n$). If $d(a) = b$ and $d(b) = a$, where $a \not= b$, then $a$ and $b$ are an amicable pair and each of $a$ and $b$ are called amic…