Ramanujan's second letter to Hardy [1]: "Dear Sir, I am very much gratified on perusing your letter of the 8th February 1913. I was expecting a reply from you

Ramanujan's second letter to Hardy [1]: "Dear Sir, I am very much gratified on perusing your letter of the 8th February 1913. I was expecting a reply from you similar to the one which a Mathematics Professor at London wrote asking me to study carefully Bromwich's Infinite Series and not fall into the pitfalls of divergent series. … I told him that the sum of an infinite number of terms of the series: 1 + 2 + 3 + 4 + ... = −1/12 under my theory. If I tell you this you will at once point out to me the lunatic asylum as my goal. I dilate on this simply to convince you that you will not be able to follow my methods of proof if I indicate the lines on which I proceed in a single letter. ..." [1] http://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4 http://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4