1 2 3 4 5 6 7 8 9 10 11 12 13
let combination = fn (n, k) => { let a = k == 0; let b = k == n; if (a || b) { 1 } else { combination(n - 1, k - 1) + combination(n - 1, k) } }; print(combination(10, 2))