Question: 
Write a function to find the nth jacobsthal number.


Model's Code:
def jacobsthal_num(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return jacobsthal_num(n - 2) + 2 * jacobsthal_num(n - 1)



Sample Correct Code:
def jacobsthal_num(n): 
	dp = [0] * (n + 1) 
	dp[0] = 0
	dp[1] = 1
	for i in range(2, n+1): 
		dp[i] = dp[i - 1] + 2 * dp[i - 2] 
	return dp[n]


Asserts:
assert jacobsthal_num(5) == 11
assert jacobsthal_num(2) == 1
assert jacobsthal_num(4) == 5


Tests:
Test 1 of 3: FAIL: AssertionError()

Test 752 of 974: 568/752 (75.53191489361703%): failed