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) |
|---|---|
| 4 | 1 |
| 5 | 7 |
| 6 | 73 |
| 7 | 747 |
| 8 | 7218 |
| 9 | 65583 |
| 10 | 567540 |
| 11 | 4725540 |
| 12 | 38145600 |
| 13 | 300244320 |
| 14 | 2314123992 |
| 15 | 17522693064 |
| 16 | 130682767824 |
| 17 | 961866429552 |
| 18 | 6998356983168 |
| 19 | 50401223526528 |
| 20 | 359691525797760 |
| 21 | 2546051729270400 |
| 22 | 17889363288835200 |
| 23 | 124855271993773440 |
| 24 | 866077921088785152 |
| 25 | 5974010552957001984 |
| 26 | 40994676513378284544 |