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 | -6 |
| 4 | 0 |
| 5 | 100 |
| 6 | 570 |
| 7 | 798 |
| 8 | -15176 |
| 9 | -163368 |
| 10 | -700650 |
| 11 | 3112450 |
| 12 | 84347868 |
| 13 | 738909444 |
| 14 | 1555721986 |
| 15 | -54879912570 |
| 16 | -955420939440 |
| 17 | -7454556070352 |
| 18 | 13202860260654 |
| 19 | 1329363428217354 |
| 20 | 20878556441998660 |
| 21 | 145324350344133660 |
| 22 | -1185240365741022822 |