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 | -3 |
| 2 | -9 |
| 3 | -288 |
| 4 | 459 |
| 5 | -19278 |
| 6 | -1539 |
| 7 | -1265301 |
| 8 | 10734525 |
| 9 | -147277926 |
| 10 | 520204923 |
| 11 | -7511358663 |
| 12 | 88687160577 |
| 13 | -668191863951 |
| 14 | 5357547144702 |
| 15 | -87542760890124 |
| 16 | 967961569696722 |
| 17 | -5115624735401361 |
| 18 | 46065749188891275 |
| 19 | -430898393089547667 |
| 20 | 6203508335817169257 |