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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5040 |
| 8 | 40320 |
| 9 | 362880 |
| 10 | 7257600 |
| 11 | 119750400 |
| 12 | 1916006400 |
| 13 | 31135104000 |
| 14 | 523069747200 |
| 15 | 10461394944000 |
| 16 | 230150688768000 |
| 17 | 5335311421440000 |
| 18 | 128047474114560000 |
| 19 | 3162772610629632000 |