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 | 1 |
| 4 | 3 |
| 5 | 16 |
| 6 | 84 |
| 7 | 579 |
| 8 | 5721 |
| 9 | 87381 |
| 10 | 2104349 |
| 11 | 78315231 |
| 12 | 4383566676 |
| 13 | 362178638727 |