First column is Meg range (for instance, 6 = 6,000,000 - 6,999,999).

Second column is the number of exponents

in that range for which at least one LL test was done, but not 2 matching LL tests, and with no P-1 factoring ever having been done for that exponent.

Code:

0 0
1 0
2 0
3 0
4 0
5 0
6 0
7 2
8 79
9 1507
10 9118
11 5972
12 4122
13 1880
14 1187
15 1062
16 1044
17 1054
18 1053
19 1069

How do we interpret these results?

At low ranges (0M - 7M), just about every exponent has been double-checked, so the numbers are zero.

The numbers then rise sharply, peaking at 10M (not sure why). Of course, many of the machines that perform the double-checks will have enough memory to do a P-1 trial-factoring before going ahead with the LL double-check. But judging by past history some won't, and some thousands of exponents will never get a P-1 test done.

From 15M-19M the numbers decline to a plateau. I'm not sure why. Maybe it's because only modern machines are fast enough to exponents in that range, and such machines are more likely to have plenty of memory (required for P-1 testing) and also more likely to have a recent version of Prime95 installed (since P-1 trial-factoring was only introduced in fairly recent version of Prime95).

If P-1 testing could be organized to get through the hump between 10M-13M, then after that it would be fairly easy to ensure that P-1 trial-factoring always kept ahead of the leading edge of double-checking (in the "plateau" region).