1729 math_blog
Now I got my second factor on mersenne.ca. This one is a factor of M9999971879:
17120076576497274889 divides M9999971879
TF 63-64
k=856006236So this is only a 64-bit factor and I am surprised it wasn't known until now. I used the Factor5 program to find it.
I got this new Mersenne factor of 22 digits while doing trial-factoring of M773,833,681.
This will be quite a long post. M11=23*89 factored year 1536 M23=47*178481 factored year 1640 M41=13367*164511353 factored year 1859 M59=179951*3203431780337 factored year 1878 M67=193707721*761838257