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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 7 |
| 5 | 42 |
| 6 | 245 |
| 7 | 1428 |
| 8 | 8379 |
| 9 | 49588 |
| 10 | 296010 |
| 11 | 1781325 |
| 12 | 10798788 |
| 13 | 65900296 |
| 14 | 404565252 |
| 15 | 2496994136 |
| 16 | 15486165555 |
| 17 | 96464124648 |
| 18 | 603262881620 |
| 19 | 3786268349115 |
| 20 | 23842082904255 |
| 21 | 150586208376450 |
| 22 | 953736669989985 |