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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 16 |
| 5 | 140 |
| 6 | 1987 |
| 7 | 62266 |
| 8 | 3899340 |
| 9 | 508317004 |
| 10 | 108388350636 |
| 11 | 44608244030240 |
| 12 | 39116330784279236 |