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 | -28 |
| 2 | 350 |
| 3 | -2576 |
| 4 | 12593 |
| 5 | -45892 |
| 6 | 149926 |
| 7 | -514504 |
| 8 | 1734264 |
| 9 | -5142508 |
| 10 | 14199108 |
| 11 | -40931240 |
| 12 | 117876241 |
| 13 | -311946824 |
| 14 | 796757922 |
| 15 | -2104447072 |
| 16 | 5482534827 |
| 17 | -13518654268 |
| 18 | 32992345904 |
| 19 | -81755033080 |
| 20 | 198688497651 |