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 | 0 |
| 2 | 9 |
| 3 | 18 |
| 4 | -306 |
| 5 | -3240 |
| 6 | 49176 |
| 7 | 1466640 |
| 8 | -13626000 |
| 9 | -1172668032 |
| 10 | 75256704 |
| 11 | 1392243773184 |
| 12 | 18426692664576 |
| 13 | -2213592367094784 |
| 14 | -74200148173310976 |
| 15 | 4271973657228822528 |
| 16 | 294089252618987845632 |
| 17 | -8526609981314268364800 |
| 18 | -1299100041545138822873088 |