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) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 24 |
| 7 | 105 |
| 8 | 510 |
| 9 | 2765 |
| 10 | 16408 |
| 11 | 105210 |
| 12 | 724580 |
| 13 | 5330149 |
| 14 | 41649828 |
| 15 | 344120777 |
| 16 | 2995027126 |
| 17 | 27368953170 |
| 18 | 261825429024 |
| 19 | 2615385871053 |
| 20 | 27216432127818 |
| 21 | 294443944669341 |
| 22 | 3305528914953420 |
| 23 | 38442535155671262 |
| 24 | 462431164589185924 |
| 25 | 5745587267806107545 |