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 | 3 |
| 2 | 18 |
| 3 | -117 |
| 4 | -1971 |
| 5 | 16119 |
| 6 | 343278 |
| 7 | -3036528 |
| 8 | -71818164 |
| 9 | 661017348 |
| 10 | 16593480504 |
| 11 | -156436510221 |
| 12 | -4080815440497 |
| 13 | 39095628518637 |
| 14 | 1047594828442626 |
| 15 | -10152600834566916 |
| 16 | -277489726161424569 |
| 17 | 2712640349690579349 |
| 18 | 75279129630178436622 |
| 19 | -740885355955719640809 |