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 | 1 |
| 6 | 53 |
| 7 | 1072 |
| 8 | 16595 |
| 9 | 211462 |
| 10 | 2431627 |
| 11 | 26393893 |
| 12 | 276101593 |
| 13 | 2816219685 |
| 14 | 28221308574 |
| 15 | 279267094107 |
| 16 | 2738556645645 |
| 17 | 26678405009130 |
| 18 | 258648302848389 |