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 | -23 |
| 5 | 1 |
| 6 | 601 |
| 7 | 2731 |
| 8 | -13775 |
| 9 | -219743 |
| 10 | -313199 |
| 11 | 15383611 |
| 12 | 125451481 |
| 13 | -811558175 |
| 14 | -20767068503 |
| 15 | -37852036949 |
| 16 | 2898343066081 |
| 17 | 28990920216001 |
| 18 | -313289894357855 |
| 19 | -8634009894555653 |
| 20 | -3214642669500599 |
| 21 | 2108734127922999361 |
| 22 | 20183394611962437241 |