When
Ramanujan approached Prof. Seshu Aiyar, at Presidency College,
with some theorems on Prime Numbers, his attention was drawn to
G.H. Hardy’s Tract on “Orders
of Infinity”. Soon, Ramanujan observed that: “On
p.36 of this Tract the exact order of 
has not yet been determined.”
In
other words, Hardy stated in the Tract that ‘no definite
expression has yet been found for the number of prime numbers
less than any given number’.
Ramanujan
discovered a result which gave the order of .
Prof. Seshu Aiyar suggested the communication of this and other
results to Mr. G.H.Hardy, by then a Fellow of the Royal Society
and a renowned British Mathematician.
