```
print [rising_factorial(n,n) for n in (0..5)]
print [rising_factorial(n,n) for n in range(6)]
```

I think both forms should give the same result. But the output is:

```
[1, 1, 6, 60, 840, 15120]
AttributeError: 'int' object has no attribute 'parent'
```

1 | initial version |

```
print [rising_factorial(n,n) for n in (0..5)]
print [rising_factorial(n,n) for n in range(6)]
```

I think both forms should give the same result. But the output is:

```
[1, 1, 6, 60, 840, 15120]
AttributeError: 'int' object has no attribute 'parent'
```

2 | No.2 Revision |

```
print [rising_factorial(n,n) for n in (0..5)]
print [rising_factorial(n,n) for n in range(6)]
```

I think both forms should give the same result. But the output is:

```
[1, 1, 6, 60, 840, 15120]
AttributeError: 'int' object has no attribute 'parent'
```

Edit: The same error is thrown for falling_factorial. Note that the factorial function does not assume Sage-integers. This is a confusing inconsistency in the interface, at least.