Big-O notation for two simple recursive functions

I have two recursive functions in Python and simply just want to know the Big O Notation for them. What is the Big O for each these?

def cost(n):
    if n == 0:
        return 1
    else:
        return cost(n-1) + cost(n-1)

def cost(n):
    if n == 0:
        return 1
    else:
        return 2*cost(n-1)