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 | 13 |
| 5 | 45 |
| 6 | 153 |
| 7 | 515 |
| 8 | 1767 |
| 9 | 6167 |
| 10 | 21697 |
| 11 | 76661 |
| 12 | 271973 |
| 13 | 968561 |
| 14 | 3460677 |
| 15 | 12399661 |
| 16 | 44534647 |
| 17 | 160285049 |
| 18 | 577949447 |
| 19 | 2087375443 |
| 20 | 7550053527 |
| 21 | 27344761057 |
| 22 | 99155777619 |
| 23 | 359943568005 |
| 24 | 1307923066305 |
| 25 | 4756914915657 |
| 26 | 17315390737219 |
| 27 | 63077564876055 |