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 | 3 |
| 3 | 12 |
| 4 | 60 |
| 5 | 360 |
| 6 | 2268 |
| 7 | 18144 |
| 8 | 152544 |
| 9 | 1471008 |
| 10 | 14963328 |
| 11 | 179559936 |
| 12 | 2156963328 |
| 13 | 30197486592 |
| 14 | 426680825088 |
| 15 | 6448500066288 |
| 16 | 103658110188528 |
| 17 | 1865845983393504 |
| 18 | 33623263082197152 |
| 19 | 672465261643943040 |
| 20 | 13457623759369050240 |
| 21 | 283699943666342340480 |
| 22 | 6265115909183775026880 |