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 | 3 |
| 2 | 10 |
| 3 | 56 |
| 4 | 120 |
| 5 | 432 |
| 6 | 12672 |
| 7 | 249600 |
| 8 | 873180 |
| 9 | 4838400 |
| 10 | 296110080 |
| 11 | 10786406400 |
| 12 | 49621572000 |
| 13 | 355053404160 |
| 14 | 34613526528000 |
| 15 | 211189410432000 |
| 16 | 1910897049600000 |
| 17 | 21311651380219200 |
| 18 | 274774815041126400 |
| 19 | 62908970812047360000 |