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 | -9 |
| 2 | 27 |
| 3 | -30 |
| 4 | 9 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | -1 |
| 10 | -9 |
| 11 | -54 |
| 12 | -273 |
| 13 | -1260 |
| 14 | -5508 |
| 15 | -23256 |
| 16 | -95931 |
| 17 | -389367 |
| 18 | -1562275 |
| 19 | -6216210 |
| 20 | -24582285 |
| 21 | -96768360 |
| 22 | -379629720 |
| 23 | -1485507600 |
| 24 | -5801732460 |
| 25 | -22626756594 |
| 26 | -88152205554 |
| 27 | -343176898988 |
| 28 | -1335293573130 |
| 29 | -5193831553416 |