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 | 3 |
| 1 | 12 |
| 2 | 120 |
| 3 | 360 |
| 4 | 1008 |
| 5 | 20160 |
| 6 | 259200 |
| 7 | 907200 |
| 8 | 6652800 |
| 9 | 19160064 |
| 10 | 39626496000 |
| 11 | 62270208000 |
| 12 | 603542016000 |
| 13 | 640493568000 |
| 14 | 1067062284288000 |
| 15 | 4001483566080000 |
| 16 | 4174096582656000 |
| 17 | 162193467211776000 |
| 18 | 13651830701752320000 |
| 19 | 481714597618974720000 |