This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 78 |
| 5 | 944 |
| 6 | 13760 |
| 7 | 235248 |
| 8 | 4620224 |
| 9 | 102551296 |
| 10 | 2539240416 |
| 11 | 69398978560 |
| 12 | 2075328010624 |
| 13 | 67408188246528 |
| 14 | 2363279141726464 |
| 15 | 88952164594807808 |
| 16 | 3577709564478865920 |
| 17 | 153136329382704201728 |
| 18 | 6950244396227548178432 |