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 | 0 |
| 2 | -2 |
| 3 | -8 |
| 4 | -34 |
| 5 | -152 |
| 6 | -714 |
| 7 | -3472 |
| 8 | -17318 |
| 9 | -88048 |
| 10 | -454378 |
| 11 | -2373048 |
| 12 | -12515634 |
| 13 | -66551016 |
| 14 | -356345666 |
| 15 | -1919453984 |
| 16 | -10392792766 |
| 17 | -56527200992 |
| 18 | -308691183938 |
| 19 | -1691769619240 |
| 20 | -9301374102034 |