JSFiddle - React, Tailwind, and code Playground

by hescano

JavaScript

function perimeter(n) {
	function fib(n) {
    var a = 0, b = 1, f = 1;
    var total = 0;
    for(var i = 2; i <= n; i++) {
        f = a + b;
        total += f;
        a = b;
        b = f;
    }
    return total + 1;
	}
    return 4 * fib(n + 1);
}

alert(perimeter(20));