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 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | -6 |
| 5 | -25 |
| 6 | -70 |
| 7 | 119 |
| 8 | 4354 |
| 9 | 48215 |
| 10 | 371610 |
| 11 | 1620839 |
| 12 | -10665886 |
| 13 | -388969945 |
| 14 | -6114636710 |
| 15 | -65181228841 |
| 16 | -325375497726 |
| 17 | 5950049261495 |
| 18 | 226564100074970 |
| 19 | 4447402833379079 |
| 20 | 57902620204276834 |
| 21 | 258292327155958535 |
| 22 | -12701483290229413350 |