# Problem with infinite sum

With Maple everything is so simple.

```
R := n -> sum(bernoulli(2*k)/n^(2*k), k = 1..infinity);
seq(evalf(R(i)), i = 1..5);
0.1449340668,0.03986813370,...
```

With Sage that's another story.

```
def R(n):
var('k')
return sum(bernoulli(2*k)/n^(2*k), k, 1, infinity)
[R(i) for i in (1..5)]
```

TypeError: unable to convert x (=2*k) to an integer. What do I miss?

EDIT with errors deleted.

Yes, you suggested import mpmath. Because of the effects you describe I always work with different worksheets, one with mpmath and one without. Of course this is peripheral here with regard to the problem.

Yes, I swapped n and k. Sorry for this. I deleted the edit.