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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 5 |
| 4 | -47 |
| 5 | 719 |
| 6 | -16299 |
| 7 | 513253 |
| 8 | -21430513 |
| 9 | 1145710573 |
| 10 | -76317960163 |
| 11 | 6197399680779 |
| 12 | -602640663660199 |
| 13 | 69134669061681469 |
| 14 | -9239224408001877873 |
| 15 | 1422887941494773642817 |
| 16 | -250160794466824215921275 |
| 17 | 49797413478450579190546203 |
| 18 | -11142367835115998962269070519 |
| 19 | 2784355004138005473128335461749 |