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 | 3 |
| 2 | 15 |
| 3 | 2520 |
| 4 | 45045 |
| 5 | 102960 |
| 6 | 232792560 |
| 7 | 5354228880 |
| 8 | 1115464350 |
| 9 | 291136195350 |
| 10 | 20629078984800 |
| 11 | 144403552893600 |
| 12 | 5342931457063200 |
| 13 | 856326196254765600 |
| 14 | 9419588158802421600 |
| 15 | 3099044504245996706400 |
| 16 | 4106233968125945635980 |
| 17 | 16424935872503782543920 |