I don't think bootkeen is wrong. The fact that the author's solution gives 6.10 means something is clearly wrong. 36 guys passing the test means the error is likely not in the algorithm, but in the internal data handling.

36 guys passed the Python kata; that is not a lot but enough to reasonably think there are no errors in the tests.

Sorry, but I cannot explain the math myself. Here is a reference though if you are interested: https://en.wikipedia.org/wiki/Square_pyramidal_number

I think I have solved this issue :)

What do you think I should do?, warning about don't use the operator ... because babel is going to transpile it to a for loop, or make a regex whick allows only this kind of loops created by babel?

What happens is that when the code is transpiled to ES5 with babel, ...predicates is transpiled to

  for (var _len = arguments.length, predicates = Array(_len), _key = 0; _key < _len; _key++) {
    predicates[_key] = arguments[_key];
  }

So the code transpiled has a for loop... I have to see who I can avoid this exception.