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 | 3 |
| 2 | -18 |
| 3 | 63 |
| 4 | -207 |
| 5 | 696 |
| 6 | -2415 |
| 7 | 8565 |
| 8 | -30714 |
| 9 | 110583 |
| 10 | -398439 |
| 11 | 1435152 |
| 12 | -5167083 |
| 13 | 18598065 |
| 14 | -66931314 |
| 15 | 240862563 |
| 16 | -866772819 |
| 17 | 3119198160 |
| 18 | -11224913079 |
| 19 | 40394716341 |
| 20 | -145367356794 |
| 21 | 523129840335 |
| 22 | -1882574375679 |
| 23 | 6774773362320 |
| 24 | -24380205972915 |