Kata

Calculating the n-th element of the fibonacci sequence is usually calculated recursively using a top down approach that causes the repeated calculation of certain elements in the sequence. The resulting function is useful only for a small n. Using iteration it is possible to calculate the sequence more efficiently because it induces the use of a bottom up approach that retains the information required to calculate the next element in the sequence. The same can be done using recursion and a helper function. Write the recursive helper function. The function should work for n = 500