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 | 1 |
| 2 | -1 |
| 3 | 5 |
| 4 | -10 |
| 5 | 22 |
| 6 | -154 |
| 7 | 374 |
| 8 | -935 |
| 9 | 21505 |
| 10 | -55913 |
| 11 | 147407 |
| 12 | -1179256 |
| 13 | 3174920 |
| 14 | -8617640 |
| 15 | 70664648 |
| 16 | -194327782 |
| 17 | 537259162 |
| 18 | -13431479050 |
| 19 | 37466757350 |
| 20 | -104906920580 |
| 21 | 884215473460 |
| 22 | -2491879970660 |
| 23 | 7042269482300 |
| 24 | -59859290599550 |