---
id: 5900f43e1000cf542c50ff4f
challengeType: 5
videoUrl: ''
title: 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);
```
## Challenge Seed
<section id='challengeSeed'>
<div id='js-seed'>
```js
function euler209() {
// Good luck!
return true;
}
euler209();
</div>
## Solution
<section id='solution'>
// solution required
/section>