Observe the rules and fill in the blanks: 1 and 1 / 2, 2 and 1 / 4, 3 and 1 / 8 The nth number is(

Observe the rules and fill in the blanks: 1 and 1 / 2, 2 and 1 / 4, 3 and 1 / 8 The nth number is(

1 / N of N and 2