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 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 16 |
| 5 | 224 |
| 6 | 608 |
| 7 | 13320 |
| 8 | 41760 |
| 9 | 1366152 |
| 10 | 4440312 |
| 11 | 215100192 |
| 12 | 655723440 |
| 13 | 48242081328 |
| 14 | 121651212720 |
| 15 | 14627299801728 |
| 16 | 24367884018048 |
| 17 | 5768946415383552 |
| 18 | 2780730890516736 |
| 19 | 2872938805170308352 |
| 20 | -2941729703083507968 |
| 21 | 1764460446550873413120 |