please give the definition and write a function in c++ code for number 3

Integers. Use Only Dun- + OF Operator in your recursive us LIVE 3. (20 points) You have the following sequence of numbers: 1, 2, 4, 7, 11, 16, 22, 29, 37, 46, 56, 67, 79, 92, ... Find the recursive rule from the above series, and give a recursive definition, and write a function that implements the definition. (Note: f(1) = 1, f(2)= 3, f(3) = 4, f(4) = 7, ...) NOTE: For questions 2 and 3 electronic submission is not required (write your code on paper)