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 | -6 |
| 3 | -24 |
| 4 | -104 |
| 5 | -530 |
| 6 | -3192 |
| 7 | -22358 |
| 8 | -178880 |
| 9 | -1609938 |
| 10 | -16099400 |
| 11 | -177093422 |
| 12 | -2125121088 |
| 13 | -27626574170 |
| 14 | -386772038408 |
| 15 | -5801580576150 |
| 16 | -92825289218432 |
| 17 | -1578029916713378 |
| 18 | -28404538500840840 |