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 | 3 |
| 3 | 15 |
| 4 | 135 |
| 5 | 819 |
| 6 | 1365 |
| 7 | 1485 |
| 8 | 2295 |
| 9 | 9009 |
| 10 | 13923 |
| 11 | 63855 |
| 12 | 387387 |
| 13 | 397575 |
| 14 | 667275 |
| 15 | 14381055 |
| 16 | 16410735 |
| 17 | 99558459 |
| 18 | 271543725 |
| 19 | 3145425129 |
| 20 | 7096702977 |
| 21 | 741585912975 |
| 22 | 2148325363107 |
| 23 | 4847048133291 |
| 24 | 39206559148911 |
| 25 | 53164445037705 |
| 26 | 130468907286855 |
| 27 | 1229923663366167 |