- A Konyagin-Pomerance proof of
(1721^2161-1)/1720 6990 x32 01 Generalized repunit
by Broadhurst, de Water and Leyland, is detailed in
It entailed two notable factorizations:
Phi(108,1721) = 757 * 2377 * 67641587029 *
Phi(180,1721) = 12601 * 10968736861 *
The first was achieved by Tomabechi SNFS, which took
4 CPU days on a 1GHz Athlon, with zero hand-holding.
Paul Leyland repeated the feat in less than 1 CPU day,
using Peter Montgomery's code, for which the
hand-holding cost is understandably greater.
The second factorization took about 1 CPU month,
spread over a variety of Paul's machines.