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 | 0 |
| 3 | -9 |
| 4 | -40 |
| 5 | 125 |
| 6 | 3444 |
| 7 | 18571 |
| 8 | -241872 |
| 9 | -5796711 |
| 10 | -24387220 |
| 11 | 1132278191 |
| 12 | 25132445832 |
| 13 | 8850583573 |
| 14 | -10681029498972 |
| 15 | -214099676807085 |
| 16 | 1643397436986464 |
| 17 | 176719161389104817 |
| 18 | 2976468247699317468 |
| 19 | -71662294521163070153 |
| 20 | -4638920054290748840520 |
| 21 | -55645074852328083377619 |