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 | 1 |
| 3 | 3 |
| 4 | 2 |
| 5 | 35 |
| 6 | 32 |
| 7 | 315 |
| 8 | 746 |
| 9 | 2304 |
| 10 | 12422 |
| 11 | 27621 |
| 12 | 150729 |
| 13 | 465387 |
| 14 | 1762427 |
| 15 | 7239244 |
| 16 | 23799382 |
| 17 | 102216580 |
| 18 | 360900542 |
| 19 | 1416054762 |
| 20 | 5522838696 |
| 21 | 20534319262 |
| 22 | 82389314900 |
| 23 | 311135342409 |
| 24 | 1223933415631 |
| 25 | 4773363130810 |
| 26 | 18490946264039 |
| 27 | 73109087367264 |
| 28 | 284357219601461 |