recursing question

[python101]

I have the code
[code=python]
def calculation(n):
print 'n =', n
if n<=1:
return n
if n%2==0:
print 'Even'
return calculation(n-1) + calculation(n-2) + 1
else:
print 'Odd'
return n

print calculation(4)

[/code]

the result is
[code=python]
n = 4
Even
n = 3
Odd
n = 2
Even
n = 1
n = 0
6
[/code]
Can anyone explain why I get this result?

And provide some other similar examples, so I can get practiced with this kind of problem?

[ilikepython]

I have the code
[code=python]
def calculation(n):
print 'n =', n
if n<=1:
return n
if n%2==0:
print 'Even'
return calculation(n-1) + calculation(n-2) + 1
else:
print 'Odd'
return n

print calculation(4)

[/code]

the result is
[code=python]
n = 4
Even
n = 3
Odd
n = 2
Even
n = 1
n = 0
6
[/code]
Can anyone explain why I get this result?

And provide some other similar examples, so I can get practiced with this kind of problem?

What result did you expect to get?

[elcron]

I have the code
[code=python]
def calculation(n):
print 'n =', n
if n<=1:
return n
if n%2==0:
print 'Even'
return calculation(n-1) + calculation(n-2) + 1
else:
print 'Odd'
return n

print calculation(4)

[/code]

the result is
[code=python]
n = 4
Even
n = 3
Odd
n = 2
Even
n = 1
n = 0
6
[/code]
Can anyone explain why I get this result?

And provide some other similar examples, so I can get practiced with this kind of problem?

This will help make it more visible.
[code=python]
def calculation(n, nesting=0):
print ' '*nesting, 'n =', n
if n<=1:
return n
if n%2==0:
print ' '*(nesting + 1), 'Even'
return calculation(n-1, nesting+1) + calculation(n-2, nesting+1) + 1
else:
print ' '*(nesting + 1), 'Odd'
return n


print calculation(4)

"""
output
n = 4
Even
n = 3
Odd
n = 2
Even
n = 1
n = 0
6
"""
[/code]