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 | -2 |
| 2 | 1 |
| 3 | 13 |
| 4 | -23 |
| 5 | -242 |
| 6 | -1559 |
| 7 | 16273 |
| 8 | -145799 |
| 9 | -4222034 |
| 10 | 3164281 |
| 11 | 3257872813 |
| 12 | 94135157041 |
| 13 | -7612225739042 |
| 14 | 563989131103537 |
| 15 | 69655619036668993 |
| 16 | 4504341812743290961 |
| 17 | -2245876068496447419362 |
| 18 | -169454688152728033203119 |