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 | -4 |
| 4 | -15 |
| 5 | -56 |
| 6 | -185 |
| 7 | -204 |
| 8 | 6209 |
| 9 | 112400 |
| 10 | 1520271 |
| 11 | 19165420 |
| 12 | 237686449 |
| 13 | 2944654296 |
| 14 | 36392001815 |
| 15 | 441823808804 |
| 16 | 5066513855745 |
| 17 | 49021548330016 |
| 18 | 202510138910239 |
| 19 | -8592616658156580 |
| 20 | -399625593156546319 |
| 21 | -12547977062999220760 |
| 22 | -350780150063930345241 |
| 23 | -9361105704321312342764 |