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 | 0 |
| 1 | 0 |
| 2 | 2 |
| 3 | 16 |
| 4 | 112 |
| 5 | 848 |
| 6 | 7032 |
| 7 | 64056 |
| 8 | 639888 |
| 9 | 6974928 |
| 10 | 82531296 |
| 11 | 1054724256 |
| 12 | 14487894144 |
| 13 | 212971227264 |