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 | 24 |
| 5 | 180 |
| 6 | 1260 |
| 7 | 9450 |
| 8 | 77952 |
| 9 | 709128 |
| 10 | 7087440 |
| 11 | 77398200 |
| 12 | 918257472 |
| 13 | 11771602128 |
| 14 | 162251002368 |
| 15 | 2393704535040 |
| 16 | 37647052591104 |
| 17 | 628913396701440 |
| 18 | 11123162442408960 |
| 19 | 207662678687208960 |