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 | 1 |
| 4 | 1 |
| 5 | -119 |
| 6 | -719 |
| 7 | -2519 |
| 8 | -6719 |
| 9 | 347761 |
| 10 | 5412961 |
| 11 | 39861361 |
| 12 | 199488961 |
| 13 | -5448797639 |
| 14 | -171814122479 |
| 15 | -2172192782759 |
| 16 | -17416977701759 |
| 17 | 251989368889441 |
| 18 | 15508068901698241 |
| 19 | 302085533813309281 |
| 20 | 3540741711640110721 |
| 21 | -21311122660066333079 |