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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | -20 |
| 6 | -135 |
| 7 | -189 |
| 8 | 3598 |
| 9 | 33300 |
| 10 | 39105 |
| 11 | -2164085 |
| 12 | -23831214 |
| 13 | -5268042 |
| 14 | 3038813869 |
| 15 | 36984819795 |
| 16 | -59749871880 |
| 17 | -8207734934984 |
| 18 | -105142191601887 |
| 19 | 482549202944307 |
| 20 | 37754304692254030 |
| 21 | 489494512692093090 |
| 22 | -4466445363328684659 |
| 23 | -271973408844483808517 |