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 | 2 |
| 3 | 8 |
| 4 | 48 |
| 5 | 376 |
| 6 | 3552 |
| 7 | 38072 |
| 8 | 433664 |
| 9 | 4677184 |
| 10 | 29762560 |
| 11 | -793410432 |
| 12 | -54950522880 |
| 13 | -2386117894016 |
| 14 | -93904016252928 |
| 15 | -3620999060747776 |
| 16 | -140559707495727104 |
| 17 | -5551125947636719616 |
| 18 | -223832352597495644160 |
| 19 | -9212210790951194357760 |
| 20 | -385841470335205512314880 |