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 | 0 |
| 3 | 6 |
| 4 | 696 |
| 5 | 6720 |
| 6 | 39840 |
| 7 | 184800 |
| 8 | 736512 |
| 9 | 2644992 |
| 10 | 8801280 |
| 11 | 27624960 |
| 12 | 82790400 |
| 13 | 238977024 |
| 14 | 668688384 |
| 15 | 1822679040 |
| 16 | 4858183680 |
| 17 | 12700876800 |
| 18 | 32647938048 |
| 19 | 82682707968 |
| 20 | 206650736640 |
| 21 | 510425825280 |
| 22 | 1247438438400 |
| 23 | 3019527684096 |
| 24 | 7245593051136 |
| 25 | 17248655769600 |