Known Distance-20 Positions in the Half-Turn Metric

All 93,659,370 known distance-20 positions as of 18 March 2014 are available below.

There are a total of 1,029,362 scrambles given. Of these, 931,750 scrambles have no symmetry or antisymmetry, and thus represent 96 distinct positions each (48 rotations and reflections, plus the 48 rotations and reflections of the inverse scramble). Another 64,987 scrambles have no symmetry but have antisymmetry, and represent 48 distinct positions each (the rotations and reflections). Of these 64,987 scrambles, 1,545 are self-inverse. The remaining 32,625 scrambles exhibit various symmetries; a breakdown of their symmetry is given by this page on symmetric positions.

Calculating the symmetry of each scramble, and the various distinct positions represented, is left as an exercise.

Before you download the large (11MB) file you might try downloading random10.txt containing 10 randomly selected, positions, or random100.txt or random1000.txt containing 100 and 1000 randomly selected positions, respectively, to ensure you can handle the format of the scrambles.

The data file is presented in zip format; this does not give the greatest compression achievable but should be readable on all systems. The enclosed htm.txt file has newlines for line terminators.

I am finding new distance-20 positoins at a rate of about 200,000 per day; I may update these files and numbers as time permits.

If you attempt to analyze this data for patterns, be aware that the process I am using to find the distance-20 positions (described here) finds them in related cosets, so there may be some apparent relationships or characteristics due just to the order of the search.

Known Distance-24 or Greater Positions in the Quarter-Turn Metric

In addition, we present all known positions at distance 24 or greater in the quarter-turn metric. There is essentially only a single known distance-26 position (with three distinct orientations); it is self-inverse, is known as superflip plus fourspot, and a scramble for it is
There are essentially only two known distance-25 positions, both immediate neighbors of the above distance-25 positions; scrambles for them are
There are only 79,780 known distance-24 positions in the quarter-turn metric. Of these, 78,820 have some form of symmetry; there are 3,324 distinct positions with respect to symmetry and antisymmetry. There are only 960 remaining positions, which are generated by orientations of the 14 non-symmetric positions with antisymmetry and the only three known non-symmetric positions without antisymmetry. These final three positions have the following scrambles:
Distance-24 positions in the quarter-turn metric lacking both symmetry and antisymmetry may be the hardest types of positions to find, even though I'm fairly certain many exist.

The data file contains scrambles for all known distance-24 or greater positions in the quarter-turn metric.