Original sentence: But it was only in September 2007 that this classical sequence found its way into the Encyclopedia of Integer Sequences (A132049).This was first proved by Leonhard Euler 1734 in a landmark paper `De summis serierum reciprocarum' (On the sums of series of reciprocals) and has fascinated mathematicians ever since
Edited sentence: But it was only in September 2007 that this classical sequence found its way into the Encyclopedia of Integer Sequences.This was first proved by Leonhard Euler in a landmark paper  ‘De summis serierum reciprocarum’ (On the sums of series of reciprocals) and has fascinated mathematicians ever since