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 | 9 |
| 2 | -27 |
| 3 | -261 |
| 4 | 765 |
| 5 | 2214 |
| 6 | -11529 |
| 7 | 11304 |
| 8 | 24813 |
| 9 | -81423 |
| 10 | 71118 |
| 11 | 106812 |
| 12 | -354609 |
| 13 | 262350 |
| 14 | 385992 |
| 15 | -1049166 |
| 16 | 739917 |
| 17 | 990306 |
| 18 | -2713203 |
| 19 | 1709604 |
| 20 | 2287710 |
| 21 | -5646600 |
| 22 | 3707532 |
| 23 | 4448952 |
| 24 | -11344833 |
| 25 | 6737319 |
| 26 | 8450838 |
| 27 | -19943757 |
| 28 | 12298248 |
| 29 | 14238558 |
| 30 | -34639974 |
| 31 | 19856736 |