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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 12 |
| 6 | 94 |
| 7 | 612 |
| 8 | 3605 |
| 9 | 19992 |
| 10 | 106644 |
| 11 | 554184 |
| 12 | 2827902 |
| 13 | 14244120 |
| 14 | 71073860 |
| 15 | 352180920 |
| 16 | 1736103460 |
| 17 | 8525167680 |
| 18 | 41741310400 |
| 19 | 203929367040 |
| 20 | 994680578505 |
| 21 | 4845761001756 |
| 22 | 23586190895078 |
| 23 | 114731538098100 |
| 24 | 557859491227841 |