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 | 1 |
| 3 | 0 |
| 4 | -3 |
| 5 | -14 |
| 6 | -39 |
| 7 | -130 |
| 8 | -263 |
| 9 | -1214 |
| 10 | -179 |
| 11 | -21810 |
| 12 | 98277 |
| 13 | -1021214 |
| 14 | 8446881 |
| 15 | -82814290 |
| 16 | 836117617 |
| 17 | -9075846014 |
| 18 | 103898533141 |
| 19 | -1257148371570 |
| 20 | 16004750729757 |
| 21 | -213975589371614 |
| 22 | 2996827456610601 |
| 23 | -43880489398997650 |
| 24 | 670443584312526697 |
| 25 | -10670445866332254014 |