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 | -3 |
| 2 | -15 |
| 3 | -66 |
| 4 | -285 |
| 5 | -1227 |
| 6 | -5280 |
| 7 | -22719 |
| 8 | -97755 |
| 9 | -420618 |
| 10 | -1809825 |
| 11 | -7787271 |
| 12 | -33506880 |
| 13 | -144172587 |
| 14 | -620342295 |
| 15 | -2669193714 |
| 16 | -11484941685 |
| 17 | -49417127283 |
| 18 | -212630811360 |
| 19 | -914902674951 |
| 20 | -3936620940675 |
| 21 | -16938396678522 |
| 22 | -72882120570585 |