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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 12 |
| 5 | 56 |
| 6 | 321 |
| 7 | 2175 |
| 8 | 17008 |
| 9 | 150504 |
| 10 | 1485465 |
| 11 | 16170035 |
| 12 | 192384876 |
| 13 | 2483177808 |
| 14 | 34554278857 |
| 15 | 515620794591 |
| 16 | 8212685046336 |
| 17 | 139062777326000 |
| 18 | 2494364438359953 |
| 19 | 47245095998005059 |
| 20 | 942259727190907180 |
| 21 | 19737566982241851720 |
| 22 | 433234326593362631601 |
| 23 | 9943659797649140568863 |