Find the rules, and then fill in. 1,3,4,7,11,18, (), (), ()

Find the rules, and then fill in. 1,3,4,7,11,18, (), (), ()

1,3,4,7,18,29,47,76
The rule is that the sum of the first two numbers equals the next number, for example, 1 + 3 = 4, 3 + 4 = 7