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 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 10 |
| 6 | 0 |
| 7 | 0 |
| 8 | 4 |
| 9 | 8 |
| 10 | 28 |
| 11 | 100 |
| 12 | 186 |
| 13 | 624 |
| 14 | 1720 |
| 15 | 7288 |
| 16 | 30666 |
| 17 | 100220 |
| 18 | 360208 |
| 19 | 1517804 |
| 20 | 7302336 |
| 21 | 29429672 |
| 22 | 139854636 |
| 23 | 753288744 |