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 | -2 |
| 2 | 30 |
| 3 | -186 |
| 4 | 838 |
| 5 | -3162 |
| 6 | 10662 |
| 7 | -33242 |
| 8 | 97830 |
| 9 | -275418 |
| 10 | 748582 |
| 11 | -1977306 |
| 12 | 5100582 |
| 13 | -12897242 |
| 14 | 32060454 |
| 15 | -78531546 |
| 16 | 189903910 |
| 17 | -454052826 |
| 18 | 1074770982 |
| 19 | -2521320410 |
| 20 | 5867287590 |
| 21 | -13554437082 |