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 | -1 |
| 2 | -1 |
| 3 | -10 |
| 4 | 11 |
| 5 | 374 |
| 6 | 9792 |
| 7 | 183847 |
| 8 | 3469427 |
| 9 | 65038049 |
| 10 | 1195396233 |
| 11 | 19667738452 |
| 12 | 189089161562 |
| 13 | -6219720781782 |
| 14 | -606316892131934 |
| 15 | -35104997710496175 |
| 16 | -1795953382595105853 |
| 17 | -88223902016631657740 |
| 18 | -4283800987347611165184 |
| 19 | -207864171877269042498096 |
| 20 | -10102590396625592962089500 |