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 | 0 |
| 1 | -1 |
| 2 | 1 |
| 3 | 0 |
| 4 | -2 |
| 5 | 1 |
| 6 | 10 |
| 7 | -13 |
| 8 | -70 |
| 9 | 163 |
| 10 | 585 |
| 11 | -2162 |
| 12 | -5361 |
| 13 | 30588 |
| 14 | 49870 |
| 15 | -459125 |
| 16 | -411370 |
| 17 | 7257651 |
| 18 | 1513653 |
| 19 | -119997558 |
| 20 | 56857538 |
| 21 | 2062729507 |
| 22 | -2444340720 |
| 23 | -36662245639 |
| 24 | 71849171621 |
| 25 | 670108236318 |
| 26 | -1904023701457 |
| 27 | -12520858710212 |
| 28 | 48731008916451 |
| 29 | 237412587011506 |
| 30 | -1237341547854760 |