chore(i18n,learn): processed translations (#44851)

curriculum/challenges/japanese/10-coding-interview-prep/project-euler/problem-407-idempotents.md

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+---
+id: 5900f5041000cf542c510016
+title: 'Problem 407: Idempotents'
+challengeType: 5
+forumTopicId: 302075
+dashedName: problem-407-idempotents
+---
+
+# --description--
+
+If we calculate $a^2\bmod 6$ for $0 ≤ a ≤ 5$ we get: 0, 1, 4, 3, 4, 1.
+
+The largest value of a such that $a^2 ≡ a\bmod 6$ is $4$.
+
+Let's call $M(n)$ the largest value of $a < n$ such that $a^2 ≡ a (\text{mod } n)$. So $M(6) = 4$.
+
+Find $\sum M(n)$ for $1 ≤ n ≤ {10}^7$.
+
+# --hints--
+
+`idempotents()` should return `39782849136421`.
+
+```js
+assert.strictEqual(idempotents(), 39782849136421);
+```
+
+# --seed--
+
+## --seed-contents--
+
+```js
+function idempotents() {
+
+  return true;
+}
+
+idempotents();
+```
+
+# --solutions--
+
+```js
+// solution required
+```