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 | -30 |
| 2 | 3780 |
| 3 | -616440 |
| 4 | 111056910 |
| 5 | -21135698280 |
| 6 | 4165203862440 |
| 7 | -840914061328320 |
| 8 | 172810940671692900 |
| 9 | -35998781800053352710 |
| 10 | 7579904611028433074280 |
| 11 | -1609957152292592382408360 |
| 12 | 344417407415742189796786680 |
| 13 | -74127324674775434904036905640 |