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 | 4 |
| 4 | -35 |
| 5 | 531 |
| 6 | -12299 |
| 7 | 400534 |
| 8 | -17277791 |
| 9 | 940844701 |
| 10 | -61860211829 |
| 11 | 4667574681056 |
| 12 | -372379676442971 |
| 13 | 24837948160750999 |
| 14 | 826269488792753097 |
| 15 | -1174087941563072053454 |
| 16 | 497371695628704851927041 |
| 17 | -188274182030170078547881991 |
| 18 | 72347643557171655842626735159 |