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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 1 |
| 9 | 3 |
| 10 | 12 |
| 11 | 60 |
| 12 | 357 |
| 13 | 2508 |
| 14 | 20100 |
| 15 | 181080 |
| 16 | 1811886 |
| 17 | 19938270 |
| 18 | 239319540 |
| 19 | 3111697260 |
| 20 | 43569197270 |
| 21 | 653597773860 |
| 22 | 10458282340380 |
| 23 | 177800134878240 |
| 24 | 3200533135400175 |
| 25 | 60812090365924905 |
| 26 | 1216273182165519240 |
| 27 | 25542270225880538760 |