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 | 60 |
| 3 | 432 |
| 4 | 7320 |
| 5 | 53680 |
| 6 | 803520 |
| 7 | 6495720 |
| 8 | 100874752 |
| 9 | 764738496 |
| 10 | 12756110400 |
| 11 | 89493288192 |
| 12 | 1568774615040 |
| 13 | 11278053084480 |
| 14 | 180228847518720 |
| 15 | 1310982643872000 |
| 16 | 22974417331646464 |
| 17 | 168479281019744640 |
| 18 | 2521788545778163200 |
| 19 | 20190830281379049600 |