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 | 0 |
| 5 | 2 |
| 6 | 20 |
| 7 | 198 |
| 8 | 2048 |
| 9 | 22468 |
| 10 | 264538 |
| 11 | 3340962 |
| 12 | 45173518 |
| 13 | 652209564 |
| 14 | 10024669626 |
| 15 | 163546399460 |
| 16 | 2823941647390 |
| 17 | 51468705947590 |
| 18 | 987671243816650 |
| 19 | 19909066390361346 |
| 20 | 420650676776338140 |
| 21 | 9297308938203169622 |
| 22 | 214562999510569012168 |