recursion example in python for loops

[cococidial]

I don't understand how this code from the python for loops example gets the answer.

def tri_recursion(k):
  if(k>0):
    result = k+tri_recursion(k-1)
    print(result)
  else:
    result = 0
  return result

print("\n\nRecursion Example Results")
tri_recursion(6)

The answer: 1, 3, 6, 10, 15, 21.

I'm still very new at python. I thought  the way the code would work is:

result = 6 + (6-1) = 11

With the presumption that k=6. I've clearly got it wrong and would be gratefully for someone to explain how the code works.

 

 

[dsonesuk]

Add current value plus total remaining values remaining below current.

6 + (5+4+3+2+1+0) = 21

Edited July 9, 2018 by dsonesuk

[cococidial]

Thanks, that makes sense finally.