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 | -2 |
| 4 | 13 |
| 5 | -29 |
| 6 | -80 |
| 7 | 1268 |
| 8 | -7351 |
| 9 | 13276 |
| 10 | 245746 |
| 11 | -3632793 |
| 12 | 27451743 |
| 13 | -63909390 |
| 14 | -1752952501 |
| 15 | 34899085656 |
| 16 | -370619158447 |
| 17 | 1779155624299 |
| 18 | 23668687715473 |
| 19 | -780307293795152 |
| 20 | 12058261763444876 |
| 21 | -107734052276914986 |
| 22 | -180664717708949253 |
| 23 | 30298196609011736398 |