

In [1]:

    
>>> def triangle(n):
...     total = n
...     if n > 0:
...         total += triangle(n - 1)
...     return total
...



In [2]:

    
triangle(4)









    Out[2]:





10



In [3]:

    
def triangle(n):
    if n <= 0:
        return 0
    return n + triangle(n - 1)



In [4]:

    
triangle(4)









    Out[4]:





10



In [5]:

    
def triangle(n):
    if n > 0:
        return n + triangle(n - 1)
    return 0



In [6]:

    
triangle(4)









    Out[6]:





10

One line, but ugly, so don't do this.



In [7]:

    
>>> def triangle(n):
...     return n + (triangle(n-1) if n>0 else 0)



In [8]:

    
triangle(4)









    Out[8]:





10



In [9]:

    
import sys



In [10]:

    
sys.getrecursionlimit()









    Out[10]:





1000



In [11]:

    
sys.setrecursionlimit(100000)



In [12]:

    
sys.getrecursionlimit()









    Out[12]:





100000