--- id: 5900f4311000cf542c50ff44 challengeType: 5 title: 'Problem 197: Investigating the behaviour of a recursively defined sequence' videoUrl: '' localeTitle: 问题197:研究递归定义的序列的行为 --- ## Description 给定函数f(x)=⌊230.403243784-x2⌋×10-9(⌊⌊是floor函数),序列un由u0 = -1和un + 1 = f(un)定义。 找到n + 1012的un + un + 1.在小数点后面给出9位数的答案。 ## Instructions ## Tests ```yml tests: - text: euler197()应该返回1.710637717。 testString: 'assert.strictEqual(euler197(), 1.710637717, "euler197() should return 1.710637717.");' ``` ## Challenge Seed ```js function euler197() { // Good luck! return true; } euler197(); ``` ## Solution ```js // solution required ```
找到n + 1012的un + un + 1.在小数点后面给出9位数的答案。
euler197()