1.2 KiB
1.2 KiB
id | challengeType | title |
---|---|---|
5900f4421000cf542c50ff55 | 5 | Problem 214: Totient Chains |
Description
By iterating φ, each positive integer generates a decreasing chain of numbers ending in 1. E.g. if we start with 5 the sequence 5,4,2,1 is generated. Here is a listing of all chains with length 4:
5,4,2,1 7,6,2,1 8,4,2,1 9,6,2,1 10,4,2,1 12,4,2,1 14,6,2,1 18,6,2,1
Only two of these chains start with a prime, their sum is 12.
What is the sum of all primes less than 40000000 which generate a chain of length 25?
Instructions
Tests
tests:
- text: <code>euler214()</code> should return 1677366278943.
testString: assert.strictEqual(euler214(), 1677366278943, '<code>euler214()</code> should return 1677366278943.');
Challenge Seed
function euler214() {
// Good luck!
return true;
}
euler214();
Solution
// solution required