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 | 5 |
| 4 | 14 |
| 5 | 74 |
| 6 | 474 |
| 7 | 3114 |
| 8 | 24240 |
| 9 | 219456 |
| 10 | 2231280 |
| 11 | 23753520 |
| 12 | 288099360 |
| 13 | 3692907360 |
| 14 | 51677246880 |
| 15 | 775999798560 |
| 16 | 12364465397760 |
| 17 | 208583679951360 |
| 18 | 3770392002048000 |
| 19 | 71251563061002240 |
| 20 | 1421847102467635200 |
| 21 | 29861872557056870400 |
| 22 | 655829140087057305600 |