JSFiddle - React, Tailwind, and code Playground

JavaScript

function factorial(n) {
    function gamma(z) {
        return Math.sqrt(2 * Math.PI / z) * Math.pow((1 / Math.E) * (z + 1 / (12 * z - 1 / (10 * z))), z);
    }
    return gamma(n + 1);
}

console.log(factorial(4));