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 | 1 |
| 2 | -4 |
| 3 | 33 |
| 4 | -376 |
| 5 | 5255 |
| 6 | -85392 |
| 7 | 1566656 |
| 8 | -31869104 |
| 9 | 710089551 |
| 10 | -17178977940 |
| 11 | 448256023501 |
| 12 | -12548355934560 |
| 13 | 375195009917364 |
| 14 | -11936772609109600 |
| 15 | 402740733371490540 |
| 16 | -14367278506882083936 |
| 17 | 540452504929440595503 |
| 18 | -21384560213508955184172 |