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 | 4 |
| 2 | 40 |
| 3 | 580 |
| 4 | 10560 |
| 5 | 226560 |
| 6 | 5532960 |
| 7 | 150570240 |
| 8 | 4501422240 |
| 9 | 146351879520 |
| 10 | 5135738294400 |
| 11 | 193376042294400 |
| 12 | 7775407679034240 |
| 13 | 332528365742227200 |
| 14 | 15073953619379719680 |
| 15 | 722117116504240994880 |
| 16 | 36458486578829035929600 |