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 | -2 |
| 2 | -10 |
| 3 | -20 |
| 4 | -90 |
| 5 | 132 |
| 6 | -836 |
| 7 | 6040 |
| 8 | 2310 |
| 9 | 60180 |
| 10 | 180308 |
| 11 | 1662568 |
| 12 | -2995620 |
| 13 | 24401320 |
| 14 | 44072120 |
| 15 | -102437328 |
| 16 | 19390406 |
| 17 | 2649221300 |
| 18 | -10584460060 |
| 19 | 14475802440 |
| 20 | -228570333836 |
| 21 | -815899620616 |
| 22 | 2088529753800 |
| 23 | -5590702681520 |
| 24 | -100828534100580 |
| 25 | -172013432412024 |