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 | 0 |
| 9 | 0 |
| 10 | 48 |
| 11 | 152 |
| 12 | 472 |
| 13 | 2696 |
| 14 | 12320 |
| 15 | 74436 |
| 16 | 429620 |
| 17 | 2515116 |
| 18 | 16122496 |
| 19 | 113016608 |
| 20 | 843492920 |
| 21 | 6575649316 |
| 22 | 54694203188 |