131.—RECENT DISCOVERIES OF LARGE PRIMES. Ever since LUCAS announced the discovery of the prime 2 127  - 1 in 1876, many attempts have been made to discover larger primes. These attempts have succeeded only recently as follows:

(a) A. FERRIER 1 has identified (2 148  + )/17 as a prime, using a method based on the converse of Fermat's theorem and a desk calculator.
(b) Using the same method and the EDSAC, WHEELER and MILLER 2,3 have proved the primality of 1 + k(2 127  - 1) for k = 114, 124, 388, 408, 498, 696, 738, 744, 780, 934, 978, and finally 1 + 180(2 127  - 1) 2 , a number of 79 decimal digits.
(c) Using the standard LUCAS test for Mersenne primes as programmed by R. M. ROBINSON, the SWAC has discovered the primes 2 521  - 1 and 2 607  - 1 on January 30, 1952. These lead to the 13th and 14th perfect numbers.
D. H. L.
    1 Letter of July 14, 1951.
    2 J. C. P. MILLER & D. J. WHEELER, "Large prime numbers," Nature, v. 168, 1951, p. 838.
    3 J. C. P. MILLER, "Large primes," Eureka, 1951, no. 14, p. 10-11.