python

The Fibonacci sequence begins with 0 and then 1 follows. All subsequent values are the sum of the previous two, ex: 0, 1, 1, 2, 3, 5, 8, 13. Complete the fibonacci() function, which has an index n as parameter and returns the nth value in the sequence. Any negative index values should return -1.

Ex: If the input is:

7 

the output is:

fibonacci(7) is 13 

Note: Use a for loop and DO NOT use recursion.

Coding

def fibonacci(n): # Type your code here.

if __name__ == '__main__': start_num = int(input()) print(f'fibonacci({start_num}) is {fibonacci(start_num)}')