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) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | -4 |
| 5 | -10 |
| 6 | -10 |
| 7 | 105 |
| 8 | 1064 |
| 9 | 6356 |
| 10 | 25080 |
| 11 | 9075 |
| 12 | -1056660 |
| 13 | -13219206 |
| 14 | -106106364 |
| 15 | -548948855 |
| 16 | 139658960 |
| 17 | 48411569800 |
| 18 | 761039099824 |
| 19 | 7815284148711 |
| 20 | 52216924707660 |
| 21 | 9385130453790 |
| 22 | -6650556642220260 |
| 23 | -132749143322588331 |
| 24 | -1713641693856894824 |