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 | 5 |
| 5 | 26 |
| 6 | 137 |
| 7 | 750 |
| 8 | 4307 |
| 9 | 25996 |
| 10 | 164825 |
| 11 | 1096217 |
| 12 | 7633650 |
| 13 | 55549664 |
| 14 | 421599778 |
| 15 | 3331027887 |
| 16 | 27349472297 |
| 17 | 232967157736 |
| 18 | 2055635993935 |
| 19 | 18762063976810 |
| 20 | 176896220650029 |
| 21 | 1720762736285790 |
| 22 | 17249873608817569 |
| 23 | 178010337967774511 |
| 24 | 1889129778601708612 |