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 | 2 |
| 3 | 3 |
| 4 | 0 |
| 5 | -55 |
| 6 | -480 |
| 7 | -3157 |
| 8 | -15232 |
| 9 | -16623 |
| 10 | 898560 |
| 11 | 16316179 |
| 12 | 194574336 |
| 13 | 1666248025 |
| 14 | 5418649600 |
| 15 | -170157839685 |
| 16 | -5164467978240 |
| 17 | -92955464490463 |
| 18 | -1188910801354752 |
| 19 | -7329026447550685 |
| 20 | 157257042777866240 |
| 21 | 7516793832172469481 |
| 22 | 187200588993188069376 |