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 | 1 |
| 2 | 6 |
| 3 | 120 |
| 4 | 198 |
| 5 | 3696 |
| 6 | 6240 |
| 7 | 32640 |
| 8 | 56160 |
| 9 | 1941408 |
| 10 | 3592200 |
| 11 | 8119800 |
| 12 | 15628032 |
| 13 | 27125280 |
| 14 | 59032080 |
| 15 | 61788240 |
| 16 | 125859840 |
| 17 | 1635834720 |
| 18 | 2147450880 |
| 19 | 3709081680 |
| 20 | 16328199552 |
| 21 | 26198072160 |
| 22 | 52344970080 |
| 23 | 52396088160 |
| 24 | 209584184160 |
| 25 | 210197601120 |
| 26 | 236223190200 |
| 27 | 237385437360 |