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 | 0 |
| 1 | 1 |
| 2 | -2 |
| 3 | 15 |
| 4 | -172 |
| 5 | 2685 |
| 6 | -53226 |
| 7 | 1281091 |
| 8 | -36296408 |
| 9 | 1183527225 |
| 10 | -43660076950 |
| 11 | 1797823266591 |
| 12 | -81746462498724 |
| 13 | 4068086310006901 |
| 14 | -219929012455113794 |
| 15 | 12835335232410655035 |
| 16 | -804287930238495495856 |
| 17 | 53858337558670992931185 |