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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 5 |
| 5 | 21 |
| 6 | 126 |
| 7 | 918 |
| 8 | 7767 |
| 9 | 73972 |
| 10 | 784751 |
| 11 | 9144147 |
| 12 | 115883755 |
| 13 | 1584170940 |
| 14 | 23204993605 |
| 15 | 362165818664 |
| 16 | 5993702566315 |
| 17 | 104749261905895 |
| 18 | 1926269870412241 |
| 19 | 37155958512895667 |
| 20 | 749685441940827386 |
| 21 | 15783243142166081008 |
| 22 | 345955075391798325101 |