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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | -2 |
| 4 | 6 |
| 5 | -30 |
| 6 | 184 |
| 7 | -1294 |
| 8 | 10034 |
| 9 | -83908 |
| 10 | 746006 |
| 11 | -6983600 |
| 12 | 68360302 |
| 13 | -696122684 |
| 14 | 7345561204 |
| 15 | -80074813040 |
| 16 | 899590031932 |
| 17 | -10394864935860 |
| 18 | 123344285904634 |
| 19 | -1500938535372826 |
| 20 | 18709376854618500 |
| 21 | -238664936823622052 |
| 22 | 3113060999816038350 |