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 | 1 |
| 2 | 2 |
| 3 | -6 |
| 4 | -32 |
| 5 | -4 |
| 6 | 312 |
| 7 | 664 |
| 8 | -1792 |
| 9 | -10224 |
| 10 | -2528 |
| 11 | 97184 |
| 12 | 219648 |
| 13 | -532544 |
| 14 | -3261568 |
| 15 | -1197696 |
| 16 | 30220288 |
| 17 | 72417536 |
| 18 | -157367808 |
| 19 | -1038910976 |
| 20 | -504143872 |
| 21 | 9380822016 |
| 22 | 23803082752 |
| 23 | -46202054656 |
| 24 | -330434936832 |
| 25 | -198849327104 |
| 26 | 2906650714112 |
| 27 | 7801794699264 |