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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | -1 |
| 7 | 2 |
| 8 | -6 |
| 9 | 24 |
| 10 | -119 |
| 11 | 717 |
| 12 | -5029 |
| 13 | 40270 |
| 14 | -362606 |
| 15 | 3627037 |
| 16 | -39903738 |
| 17 | 478892051 |
| 18 | -6225994449 |
| 19 | 87167664184 |
| 20 | -1307553837291 |
| 21 | 20921303563234 |
| 22 | -355667626509575 |
| 23 | 6402090252833481 |
| 24 | -121640761396741607 |
| 25 | 2432831275825738669 |
| 26 | -51089718792714854191 |