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 | 1 |
| 3 | 5 |
| 4 | 2 |
| 5 | 65 |
| 6 | 24 |
| 7 | 163 |
| 8 | 60 |
| 9 | 1957 |
| 10 | 720 |
| 11 | 685 |
| 12 | 252 |
| 13 | 109601 |
| 14 | 40320 |
| 15 | 98641 |
| 16 | 36288 |
| 17 | 9864101 |
| 18 | 3628800 |
| 19 | 13563139 |
| 20 | 4989600 |
| 21 | 260412269 |
| 22 | 95800320 |
| 23 | 8463398743 |
| 24 | 3113510400 |
| 25 | 47395032961 |
| 26 | 17435658240 |
| 27 | 888656868019 |
| 28 | 326918592000 |