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 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 15 |
| 6 | 45 |
| 7 | 441 |
| 8 | 441 |
| 9 | 3213 |
| 10 | 16059 |
| 11 | 172569 |
| 12 | 517671 |
| 13 | 6695325 |
| 14 | 43746885 |
| 15 | 903732249 |
| 16 | 903732249 |
| 17 | 14611840389 |
| 18 | 110769926061 |
| 19 | 1248788195355 |
| 20 | 12439562858721 |
| 21 | 154437141889677 |
| 22 | 1902100636851663 |
| 23 | 51339101124195573 |
| 24 | 255363550208935617 |
| 25 | 4458722921105347251 |