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 | -4 |
| 3 | -14 |
| 4 | 46 |
| 5 | 326 |
| 6 | -824 |
| 7 | -10604 |
| 8 | 18236 |
| 9 | 442396 |
| 10 | -378224 |
| 11 | -22498024 |
| 12 | -1695704 |
| 13 | 1348185736 |
| 14 | 1458406496 |
| 15 | -92914595024 |
| 16 | -202295082224 |
| 17 | 7230872519696 |
| 18 | 24425954508736 |
| 19 | -626352572263904 |
| 20 | -2946818250593824 |
| 21 | 59688438975796576 |
| 22 | 369104355288148096 |