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 | 2 |
| 3 | 3 |
| 4 | 16 |
| 5 | 30 |
| 6 | 480 |
| 7 | 1290 |
| 8 | 163200 |
| 9 | 471240 |
| 10 | 386400000 |
| 11 | 2269270080 |
| 12 | 12238171545600 |
| 13 | 149648961369600 |
| 14 | 8089070513113497600 |
| 15 | 160650421233958656000 |
| 16 | 91361407076595590705971200 |