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 | 2 |
| 2 | -1 |
| 3 | 6 |
| 4 | -17 |
| 5 | 71 |
| 6 | -292 |
| 7 | 1284 |
| 8 | -5807 |
| 9 | 26961 |
| 10 | -127627 |
| 11 | 613815 |
| 12 | -2990680 |
| 13 | 14730714 |
| 14 | -73229290 |
| 15 | 366936232 |
| 16 | -1851352819 |
| 17 | 9397497759 |
| 18 | -47957377933 |
| 19 | 245903408245 |
| 20 | -1266266092111 |
| 21 | 6545667052321 |
| 22 | -33954266444497 |
| 23 | 176689391245147 |
| 24 | -922112642288148 |
| 25 | 4825154135801698 |