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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 24 |
| 4 | 273 |
| 5 | 3996 |
| 6 | 70785 |
| 7 | 1465506 |
| 8 | 34662222 |
| 9 | 921511944 |
| 10 | 27201024639 |
| 11 | 882828325530 |
| 12 | 31253560065684 |
| 13 | 1198758613494852 |
| 14 | 49530067909218819 |
| 15 | 2193498057583259784 |
| 16 | 103664556373964098860 |
| 17 | 5207896547115772335552 |
| 18 | 277161367378578537506868 |