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 | 1 |
| 3 | 2 |
| 4 | -3 |
| 5 | 44 |
| 6 | -215 |
| 7 | 1014 |
| 8 | -3647 |
| 9 | 11528 |
| 10 | -35919 |
| 11 | 135530 |
| 12 | -597179 |
| 13 | 2850132 |
| 14 | -13623623 |
| 15 | 60226334 |
| 16 | -236639535 |
| 17 | 832756304 |
| 18 | -2732731487 |
| 19 | 9035612658 |
| 20 | -33172306739 |
| 21 | 138937617020 |
| 22 | -615393110199 |
| 23 | 2649206536262 |
| 24 | -10668440765663 |
| 25 | 40078777939224 |
| 26 | -142523015012975 |