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 | 35 |
| 3 | 112 |
| 4 | -1620 |
| 5 | -11648 |
| 6 | 108444 |
| 7 | 1355760 |
| 8 | -7148268 |
| 9 | -160699392 |
| 10 | 325795764 |
| 11 | 18831611120 |
| 12 | 16717398716 |
| 13 | -2145655827840 |
| 14 | -8241164160628 |
| 15 | 233713240042352 |
| 16 | 1694283113101188 |
| 17 | -23719013876232192 |
| 18 | -281341219894887740 |
| 19 | 2127341075145106800 |
| 20 | 41921238172346052044 |