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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 12 |
| 4 | 96 |
| 5 | 320 |
| 6 | 3840 |
| 7 | 161280 |
| 8 | 516096 |
| 9 | 46448640 |
| 10 | 185794560 |
| 11 | 2270822400 |
| 12 | 163499212800 |
| 13 | 1821848371200 |
| 14 | 51011754393600 |
| 15 | 10712468422656000 |
| 16 | 9794256843571200 |
| 17 | 555007887802368000 |
| 18 | 139861987726196736000 |
| 19 | 1449478781889675264000 |
| 20 | 49059281848573624320000 |