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 | 3 |
| 4 | 6 |
| 5 | -5 |
| 6 | 135 |
| 7 | -154 |
| 8 | 1260 |
| 9 | 6189 |
| 10 | -33285 |
| 11 | 470294 |
| 12 | -2056758 |
| 13 | 14299935 |
| 14 | -3614611 |
| 15 | -379101878 |
| 16 | 10041282472 |
| 17 | -121491285111 |
| 18 | 1656259499511 |
| 19 | -21619048472474 |
| 20 | 338632378045750 |
| 21 | -5874571029856693 |
| 22 | 115201962050532137 |