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 | -6 |
| 3 | 27 |
| 4 | -144 |
| 5 | 837 |
| 6 | -5139 |
| 7 | 32778 |
| 8 | -215001 |
| 9 | 1440747 |
| 10 | -9818820 |
| 11 | 67834665 |
| 12 | -473945580 |
| 13 | 3342743235 |
| 14 | -23766448545 |
| 15 | 170148578130 |
| 16 | -1225477405485 |
| 17 | 8873126329095 |
| 18 | -64547392633740 |
| 19 | 471509782020405 |
| 20 | -3457212506428230 |
| 21 | 25434642838306185 |
| 22 | -187694935991201745 |