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 | 1 |
| 4 | 2 |
| 5 | 10 |
| 6 | 46 |
| 7 | 166 |
| 8 | 504 |
| 9 | 1425 |
| 10 | 4256 |
| 11 | 14594 |
| 12 | 55783 |
| 13 | 220903 |
| 14 | 873199 |
| 15 | 3436817 |
| 16 | 13569556 |
| 17 | 53929244 |
| 18 | 215352055 |
| 19 | 861477251 |
| 20 | 3446980935 |
| 21 | 13792641374 |
| 22 | 55203566064 |
| 23 | 221112089602 |
| 24 | 887538377345 |
| 25 | 3580304912835 |
| 26 | 14573568107348 |