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 | -1 |
| 4 | -14 |
| 5 | -71 |
| 6 | -201 |
| 7 | 559 |
| 8 | 14152 |
| 9 | 125772 |
| 10 | 568873 |
| 11 | -2930247 |
| 12 | -100950588 |
| 13 | -1263405885 |
| 14 | -7645798213 |
| 15 | 62733063199 |
| 16 | 2644646815760 |
| 17 | 42203809509047 |
| 18 | 312892097907012 |
| 19 | -3774840465405301 |
| 20 | -184229592151309092 |
| 21 | -3541775382376189109 |
| 22 | -30473600413019593651 |