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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 28560 |
| 5 | 18277200 |
| 6 | 1925512560 |
| 7 | 71729634480 |
| 8 | 1389478980960 |
| 9 | 17119717947360 |
| 10 | 151217975815200 |
| 11 | 1034656343471520 |
| 12 | 5783087147848560 |
| 13 | 27431854405990320 |
| 14 | 113598910323858960 |
| 15 | 419654992044834000 |
| 16 | 1406448998999378880 |
| 17 | 4333949766504066240 |
| 18 | 12412819895060854080 |