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 | 0 |
| 3 | 0 |
| 4 | -1 |
| 5 | 4 |
| 6 | -19 |
| 7 | 107 |
| 8 | -716 |
| 9 | 5498 |
| 10 | -47789 |
| 11 | 463517 |
| 12 | -4962289 |
| 13 | 58115593 |
| 14 | -739030560 |
| 15 | 10140362326 |
| 16 | -149320366368 |
| 17 | 2348685116841 |
| 18 | -39299792354491 |
| 19 | 697018000148170 |
| 20 | -13061370974841665 |
| 21 | 257854085426453001 |
| 22 | -5349016057902489052 |
| 23 | 116324040001711961903 |
| 24 | -2646269955793816322943 |
| 25 | 62852365790563502907461 |