Composite Mersenne Number/Examples/M257/Historical Note
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Historical Note on Mersenne Number $M_{257}$
Mersenne number $M_{257}$ was the largest Mersenne number conjectured by Marin Mersenne to be prime, in his Cogitata Physico-Mathematica of $1644$.
In $1922$, Maurice Kraitchik demonstrated that it was composite, but did not find any actual factors.
Its full factorisation was eventually achieved by M.A. Penk and Robert Baillie.
It is instructive to note that, in $2017$, it took a freely-available online factorization tool $14 \cdotp 8$ seconds to perform this exact calculation.
Sources
- 1986: David Wells: Curious and Interesting Numbers ... (previous) ... (next): $2^{257} - 1$
- 1997: David Wells: Curious and Interesting Numbers (2nd ed.) ... (previous) ... (next): $2^{257} - 1$