The first four Mersenne primes , , and were known in antiquity. The fifth, , was discovered anonymously before 1461; the next two ( and ) were found by Pietro Cataldi in 1588. After nearly two centuries, was verified to be prime by Leonhard Euler in 1772. The next (in historical, not numerical order) was , found by Édouard Lucas in 1876, then by Ivan Mikheevich Pervushin in 1883. Two more ( and ) were found early in the 20th century, by R. E. Powers in 1911 and 1914, respectively.