numbers.splice(numbers[index],1);
should be changed to:
numbers.splice(index,1);

the first parameter of splice function is start index to remove, not the item

Heh jinx I beat you to it :P

Thanks!

Your code fails when n = n (string). It says in the description It's your duty to verify that n is a valid positive integer number. If not, please, return false (None for Python). so you have to return None if n is not an integer.

n(n+1) ?

n*(n+1) ?

return (n(n+1)/2) thinks you are trying to call a function instead of multiplying it - just add *.