int recursive7(int a) { int b = 0; if (a <= 1) return 1; for (int c = 1; c <= a; c++) { b = b + 2*c; } return recursive7(a/2) * recursive7(a/2) + b; }

1. Write a recurrence relation(recursive and base) which describes the running time of this function.

2. Use the repeated substitution method to solve recurrence relation and get running time.