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 | 0 |
| 2 | -4 |
| 3 | 24 |
| 4 | -135 |
| 5 | 696 |
| 6 | -3577 |
| 7 | 8738 |
| 8 | -21120 |
| 9 | 7182 |
| 10 | 85995 |
| 11 | 307692 |
| 12 | -4739379 |
| 13 | 72588316 |
| 14 | 1042545852 |
| 15 | 13023653868 |
| 16 | -40433805531 |
| 17 | -160245671048 |
| 18 | 2415459163787 |
| 19 | 80057252715814 |
| 20 | -4733090488738644 |
| 21 | 277504161503477090 |
| 22 | -7200884073495803561 |
| 23 | 97750528494490914120 |