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 | 3 |
| 4 | 24 |
| 5 | 100 |
| 6 | 1800 |
| 7 | 15435 |
| 8 | 702464 |
| 9 | 13716864 |
| 10 | 163296000 |
| 11 | 1383574500 |
| 12 | 109294479360 |
| 13 | 3842829083808 |
| 14 | 1159801183597056 |
| 15 | 132320316074821875 |
| 16 | 8213884352593920000 |
| 17 | 327816138093181337600 |
| 18 | 167079259535068179726336 |
| 19 | 34044607357920579594754944 |