---
id: 5900f43e1000cf542c50ff4f
challengeType: 5
title: 'Problem 209: Circular Logic'
videoUrl: ''
localeTitle: 问题209：循环逻辑
---

## Description
<section id="description"> k输入二进制真值表是从k个输入位（二进制数字，0 [假]或1 [真]）到1个输出位的映射。例如，逻辑AND和XOR函数的2输入二进制真值表是： <p> x y x AND y000010100111x y x XOR y000011101110多个6输入二进制真值表τ满足公式</p><p>所有6位输入（a，b，c，τ，a，b，c，d，e，f）和τ（b，c，d，e，f，一个XOR（b和c））= 0 d，e，f）？ </p></section>

## Instructions
<section id="instructions">
</section>

## Tests
<section id='tests'>

```yml
tests:
  - text: <code>euler209()</code>应该返回15964587728784。
    testString: 'assert.strictEqual(euler209(), 15964587728784, "<code>euler209()</code> should return 15964587728784.");'

```

</section>

## Challenge Seed
<section id='challengeSeed'>

<div id='js-seed'>

```js
function euler209() {
  // Good luck!
  return true;
}

euler209();

```

</div>



</section>

## Solution
<section id='solution'>

```js
// solution required
```
</section>
