W-0016
A superpermutation on 10 symbols, found by William Echols. It was the first record for n = 10, and held it from Jul 26 until Sep 29, 2026, when W-0024 was 2,152 letters shorter.
- Length
- 4,037,046
- Repeated occurrences
- 0
- Announced
- Jul 26, 2026
012345678901234567809123456780192345678012934567801239456780123495678012345967801234569780123456798012345670891234567081…
Windows
| 4,037,037 | windows of 10 consecutive letters | |
| = | 3,628,800 | distinct permutations, all 10! of them |
| + | 0 | repeated occurrences of a permutation |
| + | 408,237 | windows that are not permutations |
How it was found
Egan's length minus 1, found in the same GPT-5.6 Codex session as the n = 9 word by lifting Raudvere's n = 8 word.
Checking
| Program | Source | Result | Time |
|---|---|---|---|
| permcheck | c46d3654 | all 3,628,800 permutations appear | under 1 s |
| literal_check | f4687121 | agrees on coverage | under 1 s |
Download
Download Detour (.detour) 1.8 kB, or 4.0 MB decoded
# check it yourself
detour decode W-0016.detour - | tr -d '\n' | shasum -a 256
tar xzf checkers-rs-source.tar.gz && cd checkers-rs && cargo build --release --locked
./target/release/classcheck 10 ../W-0016.detour 4037046
./target/release/bitmapcheck 10 ../W-0016.detour 4037046
./target/release/wordhash 10 ../W-0016.detour 4037046
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 = 10 and sync exponent 0. The file has 408,177 tokens: 1 START, 1 literal of 1 byte in all, and 408,175 deviations. Deviations by weight, from 1 to 10: 0 · 408,170 · 5 · 0 · 0 · 0 · 0 · 0 · 0 · 0.