CareerCup Number of ways to take n identical objects out of a bucket

We define C(n) as the number of ways to take n identical objects out of a bucket, where objects may be taken 1, 2, or 3 at a time. 

Example: C(4)=7, because you can take 4 objects in the following 7 ways: 
1,1,1,1 
2,1,1 
1,2,1 
1,1,2 
2,2 
3,1 
1,3 

Write a function for C(n) in the language of your choice.

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It's not hard to see that C(n) has the following recursive definition (similar to the Fibonacci numbers): 
C(0)=1 
C(1)=1 
C(2)=2 
C(n)=C(n-3)+C(n-2)+C(n-1) (if n>2)