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 | 2 |
| 4 | 11 |
| 5 | 54 |
| 6 | 270 |
| 7 | 1427 |
| 8 | 7740 |
| 9 | 43260 |
| 10 | 246620 |
| 11 | 1430714 |
| 12 | 8414356 |
| 13 | 50067107 |
| 14 | 300829144 |
| 15 | 1822766463 |
| 16 | 11124747912 |
| 17 | 68328754958 |
| 18 | 422030501802 |
| 19 | 2619631042664 |
| 20 | 16332922043614 |
| 21 | 102240109896265 |
| 22 | 642312449787030 |
| 23 | 4048514844039119 |
| 24 | 25594403732709300 |
| 25 | 162250238001816845 |
| 26 | 1031147983109715120 |