EDIT (knowing that this is happening in an IPython notebook):

If you put the line

```
%load_ext sage
```

in a cell by itself and evaluate it, and then put the rest in a second cell,

```
def f(n):
for k in (1..n):
print n
f(5)
```

then your example will work.

Note that, with everything in the same cell, as you had, if after getting the
`AttributeError`

you re-evaluate the cell, then you get this warning:

```
The sage extension is already loaded. To reload it, use:
%reload_ext sage
```

but your function works and you get the expected output

```
5
5
5
5
5
```

The explanation is that `%load_ext sage`

needs to be evaluated first before the preparser is activated letting you use any Sage syntax that violates standard Python syntax rules.

I would even put the definition of f and the command `f(5)`

in different cells, so that you can work on the function definition separately from applying it to different values:

while working on the definition of `f`

(getting rid of any syntax errors), no use in trying to apply it.

once `f`

is defined, to try it with different arguments, no need to define it again each time.

Original answer:

Are you writing these lines in a Python file?

The error message seems to indicate that `(1..n)`

was parsed as trying to apply the method `.n`

to the float `1.`

, which is similar to other errors one can get when using certain Sage syntax shorthands involving a dot (`.`

) in a Python file.

Besides `(1..n)`

and `[1..n]`

, I am thinking of syntax goodies to choose names for generators of an object as you define this object, such as in these examples:

```
R.<x,y,z> = PolynomialRing(QQ)
K.<a> = NumberField(x^2 - x - 1)
F.<a,b> = FreeGroup(2)
```

If used in a Python file, these will result in an error, because Python doesn't like these uses of the dot. In a Python file the examples above would become:

```
R = PolynomialRing(QQ,['x','y','z'])
x,y,z = R.gens()
P = PolynomialRing(QQ,'x')
x = P.gen()
K = NumberField(x**2 - x - 1)
a = K.gen()
F = FreeGroup(2)
a,b = F.gens()
```

(with appropriate import statements at the start of the file).

Could you give more details on what exactly to do on cloud.sagemath.org to reproduce this?

Create a new IPython notebook, copy the five lines given. That's all.