Collatz Conjecture with JavaScript: Simple link-less levels

collatz1.js

function collatz(maxLevels){
    let levels = [[1]]
    while (levels.length < maxLevels) {
        let level = [];
        levels[levels.length-1].forEach(function(num){
            const mod6 = ((num-4)%6);
            const odd = (num-1)/3;
            if (!mod6 && odd != 1) {
                level.push(odd)
            }
            level.push(num*2);
        })
        levels.push(level);
    }
    return levels;
}

console.log(collatz(5))
// [[1], [2], [4], [8], [16]]

console.log(collatz(6))
// [[1], [2], [4], [8], [16], [5, 32]]

console.log(collatz(8))
// [[1], [2], [4], [8], [16], [5, 32], [10, 64], [3, 20, 21, 128]]