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 | 12 |
| 4 | 56 |
| 5 | 285 |
| 6 | 1533 |
| 7 | 8571 |
| 8 | 49311 |
| 9 | 290019 |
| 10 | 1735845 |
| 11 | 10538550 |
| 12 | 64741482 |
| 13 | 401708635 |
| 14 | 2513837901 |
| 15 | 15847466748 |
| 16 | 100547969532 |
| 17 | 641570954283 |
| 18 | 4114313131809 |
| 19 | 26503231512588 |
| 20 | 171416266008912 |
| 21 | 1112726163448431 |
| 22 | 7247066415484731 |