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 | 1 |
| 1 | 9 |
| 2 | 108 |
| 3 | 1620 |
| 4 | 29160 |
| 5 | 612360 |
| 6 | 14696640 |
| 7 | 396809280 |
| 8 | 11904278400 |
| 9 | 392841187200 |
| 10 | 14142282739200 |
| 11 | 551549026828800 |
| 12 | 23165059126809600 |
| 13 | 1042427660706432000 |
| 14 | 50036527713908736000 |
| 15 | 2551862913409345536000 |
| 16 | 137800597324104658944000 |
| 17 | 7854634047473965559808000 |