146.—TWO
NEW MERSENNE
PRIMES.
The program described in Notes
131(c) and
138 [MTAC,
v. 6, p. 61, 204] has been continued. Two more Mersenne
primes , 22203 - 1
and 22281 - 1,
were discovered by the SWAC on October 7 and 9, 1952. The time
required for either of the tests is one hour. This makes 17 Mersenne
primes, and a corresponding number of perfect numbers, now known. They
are 2n - 1
for n = 2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607,
1279, 2203, and 2281.
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