All Mersenne prime exponents below 100m tested at least once
Looking at the recent history:<p><pre><code>  2020-11-27 All exponents below 99 million tested at least once.
  2020-11-17 All exponents below 98 million tested at least once.
  2020-11-17 All exponents below 97 million tested at least once.
  2020-11-09 All exponents below 96 million tested at least once.
  2020-11-03 All exponents below 95 million tested at least once.
  2020-10-24 All exponents below 94 million tested at least once.
  2020-10-09 All exponents below 93 million tested at least once.
  2020-10-04 All exponents below 92 million tested at least once.
  2020-06-20 All exponents below 91 million tested at least once.
  2020-04-09 All exponents below 90 million tested at least once.
  2020-03-01 All exponents below 89 million tested at least once.
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What happened in June&#x2F;July that caused it to stop, and in October to make it suddenly restart? Did they just switch from sequential to a grouping that checked all but a small portion of each million undone until November?<p><pre><code>  September 17, 2020 All tests below 53 million verified.
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Makes me think part of it is them spending extra time verifying old tests. Just curious 1. if that&#x27;s all it is and 2. why &#x2F; whether this was triggered by something. Was there a bug found that raised doubt in previous tests?<p><i>EDIT: Formatting</i>