Which Indian mathematician's notebooks stunned Cambridge in 1913?

Ramanujan, a clerk in Madras with no formal training beyond school, who wrote to several English mathematicians enclosing pages of results. Two dismissed him. G.H. Hardy read them, initially suspected a fraud, and concluded that nobody would have the imagination to invent them - they must be true because no one could have made them up.

He worked without proofs, which was the difficulty. He produced formulas by a process he attributed to a family goddess appearing in dreams, and Hardy spent years trying to supply the rigour and to teach him a discipline he had never needed. Some results were wrong; a great many were right and are still generating work - a set of functions from his last letter, the mock theta functions, was only properly understood in 2002.

He died at 32, having been ill throughout his time in England - probably hepatic amoebiasis, misdiagnosed at the time - and unhappy in a cold country whose vegetarian food was inadequate during wartime rationing. Hardy, asked to rate mathematicians out of 100, gave himself 25, his collaborator Littlewood 30, Hilbert 80 and Ramanujan 100.