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 | 3 |
| 5 | 12 |
| 6 | 5 |
| 7 | 72 |
| 8 | 315 |
| 9 | 2240 |
| 10 | 567 |
| 11 | 1814400 |
| 12 | 77 |
| 13 | 239500800 |
| 14 | 868725 |
| 15 | 7175168 |
| 16 | 49116375 |
| 17 | 2092278988800 |
| 18 | 14889875 |
| 19 | 3201186852864000 |
| 20 | 14849255421 |
| 21 | 3783802880000 |
| 22 | 3543572316375 |
| 23 | 562000363888803840000 |
| 24 | 2505147019375 |
| 25 | 496358721386591551488 |