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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 45 |
| 7 | 1470 |
| 8 | 43890 |
| 9 | 1291815 |
| 10 | 38710035 |
| 11 | 1199167200 |
| 12 | 38692476900 |
| 13 | 1304976397725 |
| 14 | 46070080281225 |
| 15 | 1702810398539250 |
| 16 | 65862570279255750 |
| 17 | 2663551451057371875 |
| 18 | 112503209942059311375 |
| 19 | 4957166849516125744500 |