W-0066
A superpermutation on 12 symbols, found by Jakub Halfar. It beat the previous record, W-0064, by 124 letters, and was the record for n = 12 from Oct 6 until Oct 17, 2026, when W-0069 was 1 letter shorter.
- Length
- 522,737,175
- Repeated occurrences
- 177,466
- Announced
- Oct 6, 2026
0123456789AB0123456789A0B123456789A01B23456789A012B3456789A0123B456789A01234B56789A012345B6789A0123456B789A01234567B89A0…
Windows
| 522,737,164 | windows of 12 consecutive letters | |
| = | 479,001,600 | distinct permutations, all 12! of them |
| + | 177,466 | repeated occurrences of a permutation |
| + | 43,558,098 | windows that are not permutations |
How it was found
Further improvement on the new selection; Halfar's library kernel-checks HasWord 12 522737175 in Lean (group post 2026-10-06 23:48 UTC).
Checking
Total check time: 10 s, including preparation but not time in the queue.
| Program | Source | Result | Time |
|---|---|---|---|
| classcheck | 41928cce | all 479,001,600 permutations appear, by rotation class | 3 s |
| bitmapcheck | 288b3f67 | agrees, by Lehmer rank | 3 s |
| wordhash | 94925fe4 | the SHA-256 of the word and of its mirror | 3 s |
Download
Download Detour (.detour) 59.5 kB, or 522.7 MB decoded
# check it yourself
detour decode W-0066.detour - | tr -d '\n' | shasum -a 256
tar xzf checkers-rs-source.tar.gz && cd checkers-rs && cargo build --release --locked
./target/release/classcheck 12 ../W-0066.detour 522737175
./target/release/bitmapcheck 12 ../W-0066.detour 522737175
./target/release/wordhash 12 ../W-0066.detour 522737175
Decoding needs detour; see the Detour format for how to build and install it. The checkers are in checkers-rs-source.tar.gz, which needs Rust 1.89 or later; each one decodes the file itself, so the word is never written out.
The file's header gives n = 12 and sync exponent 0. The file has 5,194,010 tokens: 1 START, 1 literal of 1 byte in all, and 5,194,008 deviations. Deviations by weight, from 1 to 12: 177,466 · 1,409,804 · 3,605,021 · 285 · 121 · 843 · 98 · 137 · 186 · 28 · 19 · 0.