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 | 5 |
| 2 | 12 |
| 3 | 42 |
| 4 | 192 |
| 5 | 1080 |
| 6 | 7200 |
| 7 | 55440 |
| 8 | 483840 |
| 9 | 4717440 |
| 10 | 50803200 |
| 11 | 598752000 |
| 12 | 7664025600 |
| 13 | 105859353600 |
| 14 | 1569209241600 |
| 15 | 24845812992000 |
| 16 | 418455797760000 |
| 17 | 7469435990016000 |
| 18 | 140852221526016000 |