Combinations

function combinations(input) {
    let n = parseInt(input[0]),
        combinations = 0;

    for (let a = 0; a <= n; a++) {
        for (let b = 0; b <= n; b++) {
            for (let c = 0; c <= n; c++) {
                if (a + b + c === n){
                    combinations++;
                }
            }
        }
    }

    console.log(combinations);
}