JSFiddle - React, Tailwind, and code Playground

by dumptyd

JavaScript

const findSequence = (num) => {
  const sequence = [];
  let last = num;
  while (last !== 1) {
    last = last % 2 ? ((last * 3) + 1) : (last / 2);
    sequence.push(last);
  }
  return sequence;
}

let [num, sequence] = [0, []];
while (sequence.length < 100 && ++num) sequence = findSequence(num);

document.body.innerHTML = [
  `Number: ${num}`,
  `Length: ${sequence.length}`,
  `Array: <pre>${JSON.stringify(sequence, null, 2)}</pre>`
].join('<br>');