Adding a '+' to the end, before the '..' makes it work again, maybe it needs an operand and the '..' to show that it is an infinite series, maybe ! http://www.

Adding a '+' to the end, before the '..' makes it work again, maybe it needs an operand and the '..' to show that it is an infinite series, maybe ! http://www.wolframalpha.com/input/?i=1+-+2+%2B+3+-+4+%2B+5+-6+%2B+7%2B. http://www.wolframalpha.com/input/?i=1+-+2+%2B+3+-+4+%2B+5+-....