Problem 8. Calculate 1 + 1!/X + 2!/X^2 + … + N!/X^N

// Problem 8. Calculate 1 + 1!/X + 2!/X^2 + … + N!/X^N
//
// Write a program that, for a given two integer numbers n and x, calculates the sum S = 1 + 1!/x + 2!/x2 + … + n!/x^n.
//
// Use only one loop. Print the result with 5 digits after the decimal point.
// Note that each element can be calculated from the previous by this "formula": (previous_element) * i / x
//
// Examples:
// n    x   S
// 3    2   2.75000
// 4    3   2.07407
// 5    -4  0.75781
let input = ['3', '2'];

let print = this.print || console.log;
let gets = this.gets || ((arr, index) => () => arr[index++])(input, 0);

let n = Number(gets());
let x = Number(gets());

let s = 1;
let result = 1;

for (let i = 1; i <= n; i++){
    result = result * i;
    s = s + result / Math.pow(x, i);
}
console.log(s.toFixed(5))