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) |
|---|---|
| 2 | 1 |
| 3 | -312 |
| 4 | -121680 |
| 5 | 1004000 |
| 6 | 37942020 |
| 7 | -801594864 |
| 8 | 6139193600 |
| 9 | -11831002560 |
| 10 | -151614128250 |
| 11 | 1346611783000 |
| 12 | -4592794000704 |
| 13 | 3738595861728 |
| 14 | 15192491492360 |
| 15 | 47281379454000 |
| 16 | -737660590018560 |
| 17 | 2662090686805056 |
| 18 | -3290770281735027 |
| 19 | -4884703150768920 |