Yes, this is the initial test + double check on M3936727 = 2

^{3936727}-1

Code:

LL
Status Date User Residue Shift
Verified (Factored) 1998-01-26 Soh Kok Hong 7D98BB85E98906AA 0
Verified (Factored) 1999-12-01 Rob Simons 7D98BB85E98906AA 2768285

Then the 1st factor was found and we check if the remaining cofactor M3936727 / 1416543718452177641 is prime or composite. This is not part of the main GIMPS project to find Mersenne Primes, but a side project to find as many factors as possible and check if we found them all for each exponent.

The first 2 PRP Cofactor tests was in 2017 before PRP Certification / Proof and I think back then when PRP CF was just implemented only "Type 1" test was available.

Then 2nd factor was found and now we test the remaining cofactor: M3936727 / (1416543718452177641*2542680988412771022521) so it gives a different residue with 2 factors, and this time with a "Type 5" test, which will give a different residue from Type 1 even if the number of factors was the same.

The advantage of Type 5 is if a 3rd factor is found and Type 5 is run on the remaining cofactor, it will give the same residue as with 2 factors, so only 1 test is needed (and no PRP Certification needed). This advantaged with Type 5 is not that important now that we have PRP Certifications.

Code:

PRP Cofactor
Status Date User Residue Number of known factors Shift Type Base
Verified (Factored) 2022-06-03 Loic 70D58841F6D82E77 2 3198615 5 3
Verified (Factored) 2017-12-30 Oliver Kruse 81659F6303C264C5 1 1531080 1 3
Verified (Factored) 2017-09-20 kkmrkkblmbrbk 81659F6303C264C5 1 0 1 3