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) |
|---|---|
| 1 | 1 |
| 2 | -1 |
| 3 | 3 |
| 4 | -23 |
| 5 | 425 |
| 6 | -18129 |
| 7 | 1721419 |
| 8 | -353654167 |
| 9 | 153923102577 |
| 10 | -139765654884545 |
| 11 | 261831303051976691 |
| 12 | -1003756293946036677111 |
| 13 | 7827579773381983088436313 |
| 14 | -123626888505819540001029957073 |