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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 24 |
| 6 | 60 |
| 7 | 240 |
| 8 | 1260 |
| 9 | 8064 |
| 10 | 36288 |
| 11 | 241920 |
| 12 | 1995840 |
| 13 | 19160064 |
| 14 | 124540416 |
| 15 | 1162377216 |
| 16 | 13076743680 |
| 17 | 167382319104 |
| 18 | 1422749712384 |
| 19 | 17072996548608 |
| 20 | 243290200817664 |
| 21 | 3892643213082624 |
| 22 | 34060628114472960 |
| 23 | 428190753439088640 |
| 24 | 6463004184721244160 |