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 | -16 |
| 2 | 97 |
| 3 | -531 |
| 4 | 3148 |
| 5 | -20940 |
| 6 | 156680 |
| 7 | -1310840 |
| 8 | 12166096 |
| 9 | -124281120 |
| 10 | 1387313520 |
| 11 | -16813355280 |
| 12 | 219967479744 |
| 13 | -3090914335104 |
| 14 | 46439677053120 |
| 15 | -743069262651840 |
| 16 | 12616998421804416 |
| 17 | -226608929801923968 |
| 18 | 4292762009479969536 |
| 19 | -85545808260446050560 |
| 20 | 1789078468694176410624 |