Integers have sum of squared divisors as perfect square in JavaScript

JavascriptWeb DevelopmentFront End Technology

Problem

We are required to write a JavaScript function that takes in a range specified by an array of two numbers m and n.

Our function is supposed to find all integers between m and n (m and n integers such as 1 <= m <= n) such that the sum of their squared divisors is itself a square.

It should return an array of subarrays. The subarrays will have two elements: first the number the squared divisors of which is a square and then the sum of the squared divisors.

Example

Following is the code −

 Live Demo

const range = [1, 500];
const listSquared = ([m, n]) => {
   const res = [];
   for (let i = m; i <= n; ++i) {
      let sum = getDivisors(i).reduce((sum, n) => sum + n * n, 0);
      let ok = Number.isInteger(Math.sqrt(sum));
      if (ok) {
         res.push([i, sum]);
      }
   }
   return res;
}
function getDivisors (n) {
   const divisors = [];
   for (let i = 1; i <= n / 2; ++i) {
      if (n % i) {
         continue;
      }
      divisors.push(i);
   }
   return divisors.concat([n]);
}
console.log(listSquared(range));

Output

[ [ 1, 1 ], [ 42, 2500 ], [ 246, 84100 ], [ 287, 84100 ] ]
raja
Published on 19-Apr-2021 11:03:15
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