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 | 1 |
| 2 | -2 |
| 3 | 6 |
| 4 | -8 |
| 5 | 40 |
| 6 | 48 |
| 7 | 784 |
| 8 | 5248 |
| 9 | 49536 |
| 10 | 490240 |
| 11 | 5403904 |
| 12 | 64822272 |
| 13 | 842742784 |
| 14 | 11798284288 |
| 15 | 176974510080 |
| 16 | 2831591636992 |
| 17 | 48137058942976 |
| 18 | 866467058614272 |
| 19 | 16462874118651904 |
| 20 | 329257482362552320 |
| 21 | 6914407129635618816 |
| 22 | 152116956851937476608 |
| 23 | 3498690007594658430976 |