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 | 1 |
| 2 | 6 |
| 3 | -9 |
| 4 | -244 |
| 5 | -39 |
| 6 | 11262 |
| 7 | 36971 |
| 8 | -268890 |
| 9 | -3724293 |
| 10 | -24899558 |
| 11 | 159971919 |
| 12 | 3851093928 |
| 13 | 9663394063 |
| 14 | -197371002600 |
| 15 | -2108992348026 |
| 16 | -9447769941412 |
| 17 | 111942512192787 |
| 18 | 2253965670439788 |
| 19 | 7917705821761592 |
| 20 | -100488750700889250 |
| 21 | -1520857626228210483 |