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 | -41 |
| 3 | -423 |
| 4 | 4881 |
| 5 | 99243 |
| 6 | -922521 |
| 7 | -32540463 |
| 8 | 225260961 |
| 9 | 13691968083 |
| 10 | -60291528201 |
| 11 | -7026858626103 |
| 12 | 12079764632241 |
| 13 | 4252354469558523 |
| 14 | 4905216397718919 |
| 15 | -2961932479497809343 |
| 16 | -12564709736782617279 |
| 17 | 2331851854387899622563 |
| 18 | 17675558839428923554839 |