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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 713 |
| 8 | 664 |
| 9 | 216 |
| 10 | -4320 |
| 11 | -54720 |
| 12 | -664560 |
| 13 | -664547 |
| 14 | -664378 |
| 15 | -661830 |
| 16 | -620880 |
| 17 | 78000 |
| 18 | 12701520 |
| 19 | 12701501 |
| 20 | 12701140 |
| 21 | 12693540 |
| 22 | 12525960 |
| 23 | 8663640 |
| 24 | -84207600 |
| 25 | -84207575 |
| 26 | -84206950 |
| 27 | -84190050 |
| 28 | -83716200 |
| 29 | -69957000 |
| 30 | 343310400 |
| 31 | 343310369 |