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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | -20 |
| 5 | -159 |
| 6 | -594 |
| 7 | 2465 |
| 8 | 69560 |
| 9 | 665665 |
| 10 | 1593850 |
| 11 | -67177791 |
| 12 | -1413216540 |
| 13 | -12990964063 |
| 14 | 64480265318 |
| 15 | 4811655319393 |
| 16 | 90259507840240 |
| 17 | 540272971703937 |
| 18 | -20890652777843598 |
| 19 | -798235260367432831 |
| 20 | -12766815370452348580 |