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 | 1 |
| 4 | 4 |
| 5 | 16 |
| 6 | 136 |
| 7 | 736 |
| 8 | 4096 |
| 9 | 20224 |
| 10 | 326656 |
| 11 | 2970496 |
| 12 | 33826816 |
| 13 | 291237376 |
| 14 | 2129910784 |
| 15 | 13607197696 |
| 16 | 324498374656 |
| 17 | 4599593353216 |
| 18 | 52741679343616 |
| 19 | 495632154179584 |
| 20 | 7127212838772736 |
| 21 | 94268828128854016 |
| 22 | 2098358019107700736 |
| 23 | 34030412427789500416 |