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 | 3 |
| 3 | 6 |
| 4 | 28 |
| 5 | 120 |
| 6 | 740 |
| 7 | 5040 |
| 8 | 40416 |
| 9 | 362898 |
| 10 | 3629400 |
| 11 | 39916800 |
| 12 | 479006070 |
| 13 | 6227020800 |
| 14 | 87178326480 |
| 15 | 1307674369200 |
| 16 | 20922790210656 |
| 17 | 355687428096000 |
| 18 | 6402373709004720 |
| 19 | 121645100408832000 |
| 20 | 2432902008212929224 |
| 21 | 51090942171709545840 |
| 22 | 1124000727778046764800 |