How to make Ulam number sequence in JavaScript?

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

A mathematician Ulam proposed generating a sequence of numbers from any positive integer n (n>0) as follows −

If n is 1, it will stop.
if n is even, the next number is n/2.
if n is odd, the next number is 3 * n + 1.
continue with the process until reaching 1.

Here are some examples for the first few integers −

2->1
3->10->5->16->8->4->2->1
4->2->1
6->3->10->5->16->8->4->2->1
7->22->11->34->17->52->26->13->40->20->10->5->16->8->4->2->1

We are required to write a JavaScript function that takes in a number and returns the Ulam sequence starting with that number.

Example

The code for this will be −

const num = 7;
const generateUlam = num => {
   const res = [num];
   if(num && num === Math.abs(num) && isFinite(num)){
      while (num !== 1) {
         if(num % 2){
            num = 3 * num + 1
         }else{
            num /= 2;
         };
         res.push(num);
      };
   }else{
      return false;
   };
   return res;
};
console.log(generateUlam(num));
console.log(generateUlam(3));

Output

And the output in the console will be −

[
   7, 22, 11, 34, 17, 52, 26,
   13, 40, 20, 10, 5, 16, 8,
   4, 2, 1
]
[
   3, 10, 5, 16,
   8, 4, 2, 1
]
raja
Updated on 20-Nov-2020 09:54:33

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