--- id: 5900f5311000cf542c510042 challengeType: 5 title: 'Problem 451: Modular inverses' videoUrl: '' localeTitle: '' --- ## Description 考虑数字15.有八个正数小于15,它们与15:1,2,4,7,8,11,13,14相互作用。这些数模15的模数逆是:1,8,4 ,13,2,11,7,14因为1 * 1 mod 15 = 1 2 * 8 = 16 mod 15 = 1 4 * 4 = 16 mod 15 = 1 7 * 13 = 91 mod 15 = 1 11 * 11 = 121 mod 15 = 1 14 * 14 = 196 mod 15 = 1 设I(n)是小于n-1的最大正数m,使得m modulo n的模逆与m本身相等。所以我(15)= 11。我(100)= 51和I(7)= 1。 求3Σn≤2·107的ΣI(n) ## Instructions ## Tests ```yml tests: - text: '' testString: 'assert.strictEqual(euler451(), 153651073760956, "euler451() should return 153651073760956.");' ``` ## Challenge Seed ```js function euler451() { // Good luck! return true; } euler451(); ``` ## Solution ```js // solution required ```
设I(n)是小于n-1的最大正数m,使得m modulo n的模逆与m本身相等。所以我(15)= 11。我(100)= 51和I(7)= 1。
求3Σn≤2·107的ΣI(n)
euler451()