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 | 0 |
| 1 | 0 |
| 2 | 3 |
| 3 | 60 |
| 4 | 990 |
| 5 | 16485 |
| 6 | 292215 |
| 7 | 5602338 |
| 8 | 116549370 |
| 9 | 2627202105 |
| 10 | 63960690420 |
| 11 | 1675359272730 |
| 12 | 47031228602358 |
| 13 | 1409683851264780 |
| 14 | 44956320071089245 |
| 15 | 1520493296271210030 |
| 16 | 54376042036599780570 |
| 17 | 2050556012681642525763 |
| 18 | 81336729496634645414265 |
| 19 | 3385729099078381669910310 |