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 | 1 |
| 2 | 4 |
| 3 | 6 |
| 4 | 144 |
| 5 | 240 |
| 6 | 8640 |
| 7 | 15120 |
| 8 | 403200 |
| 9 | 725760 |
| 10 | 43545600 |
| 11 | 79833600 |
| 12 | 201180672000 |
| 13 | 373621248000 |
| 14 | 2092278988800 |
| 15 | 3923023104000 |
| 16 | 1883051089920000 |
| 17 | 3556874280960000 |
| 18 | 2688996956405760000 |
| 19 | 5109094217170944000 |
| 20 | 1605715325396582400000 |
| 21 | 3065456530302566400000 |