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 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 6 |
| 7 | 18 |
| 8 | 72 |
| 9 | 288 |
| 10 | 1440 |
| 11 | 7200 |
| 12 | 43200 |
| 13 | 259200 |
| 14 | 1814400 |
| 15 | 12700800 |
| 16 | 101606400 |
| 17 | 812851200 |
| 18 | 7315660800 |
| 19 | 65840947200 |
| 20 | 658409472000 |
| 21 | 6584094720000 |
| 22 | 72425041920000 |
| 23 | 796675461120000 |
| 24 | 9560105533440000 |
| 25 | 114721266401280000 |
| 26 | 1491376463216640000 |