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 | -2 |
| 3 | 8 |
| 4 | -42 |
| 5 | 258 |
| 6 | -1764 |
| 7 | 13070 |
| 8 | -103262 |
| 9 | 860812 |
| 10 | -7516306 |
| 11 | 68380986 |
| 12 | -645635800 |
| 13 | 6307334042 |
| 14 | -63602862362 |
| 15 | 660771763808 |
| 16 | -7061440267362 |
| 17 | 77524521343282 |
| 18 | -873398761544252 |
| 19 | 10087973928531918 |
| 20 | -119358929179189278 |
| 21 | 1445596845096459108 |
| 22 | -17909930113246116338 |