1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
x = () x = a x = a, x = a, 2 x = a, 2, x = a, 2, 3 x = a, 2, 3, 4 x = a, 2, 3, 4, 5 x = () x = (a) x = (a,) x = (a, 2) x = (a, 2,) x = (a, 2, 3) x = (a, 2, 3, 4) x = (a, 2, 3, 4, 5)