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) |
|---|---|
| 3 | 1 |
| 4 | 1 |
| 5 | 4 |
| 6 | 20 |
| 7 | 115 |
| 8 | 723 |
| 9 | 4835 |
| 10 | 33832 |
| 11 | 245089 |
| 12 | 1824893 |
| 13 | 13893810 |
| 14 | 107749252 |
| 15 | 848696376 |
| 16 | 6774097185 |
| 17 | 54692748147 |
| 18 | 446021523425 |
| 19 | 3669543413721 |
| 20 | 30427671594741 |
| 21 | 254076922595096 |
| 22 | 2134989658404402 |
| 23 | 18042590178781082 |
| 24 | 153267162148483634 |
| 25 | 1308129496836500296 |