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 | 17 |
| 3 | -123 |
| 4 | 1001 |
| 5 | -8739 |
| 6 | 79969 |
| 7 | -756939 |
| 8 | 7349657 |
| 9 | -72798003 |
| 10 | 732681489 |
| 11 | -7471545435 |
| 12 | 77031538377 |
| 13 | -801616570947 |
| 14 | 8408819677377 |
| 15 | -88821190791915 |
| 16 | 943928491520249 |
| 17 | -10085451034660947 |
| 18 | 108275140773938545 |
| 19 | -1167408859459660923 |
| 20 | 12635538801834255401 |