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) |
|---|---|
| 2 | 1 |
| 3 | 5 |
| 4 | 24 |
| 5 | 128 |
| 6 | 770 |
| 7 | 5190 |
| 8 | 38864 |
| 9 | 320704 |
| 10 | 2894544 |
| 11 | 28382800 |
| 12 | 300575968 |
| 13 | 3419882304 |
| 14 | 41612735632 |
| 15 | 539295974000 |
| 16 | 7417120846080 |
| 17 | 107904105986048 |
| 18 | 1655634186628352 |
| 19 | 26721851169634560 |
| 20 | 452587550053179392 |
| 21 | 8026445538106839040 |
| 22 | 148751109541600495104 |