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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 666 |
| 8 | 954 |
| 9 | 8586 |
| 10 | 26811 |
| 11 | 58725 |
| 12 | 173259 |
| 13 | 1189485 |
| 14 | 3898206 |
| 15 | 1077462 |
| 16 | 17239392 |
| 17 | 34789338 |
| 18 | 238787595 |
| 19 | 275338926 |
| 20 | 2019994119 |
| 21 | 578463687 |
| 22 | 2265847911 |
| 23 | 52114501953 |
| 24 | 121029900948 |
| 25 | 201452158890 |
| 26 | 1848601693368 |
| 27 | 4158660811014 |
| 28 | 2058540433587 |
| 29 | 36820880119062 |