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) |
|---|---|
| 3 | 6 |
| 4 | 48 |
| 5 | 420 |
| 6 | 3840 |
| 7 | 38010 |
| 8 | 407904 |
| 9 | 4739112 |
| 10 | 59405760 |
| 11 | 800309070 |
| 12 | 11542072080 |
| 13 | 177536452236 |
| 14 | 2902434644928 |
| 15 | 50271450894210 |
| 16 | 919799178083520 |
| 17 | 17730187503894480 |
| 18 | 359183503307677824 |
| 19 | 7629999730919490582 |
| 20 | 169605272611054951920 |
| 21 | 3937616869933172881140 |