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 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 80 |
| 6 | 322 |
| 7 | 1348 |
| 8 | 5814 |
| 9 | 25674 |
| 10 | 115566 |
| 11 | 528528 |
| 12 | 2449746 |
| 13 | 11485068 |
| 14 | 54377288 |
| 15 | 259663576 |
| 16 | 1249249981 |
| 17 | 6049846848 |
| 18 | 29469261934 |
| 19 | 144293491564 |
| 20 | 709806846980 |
| 21 | 3506278661820 |
| 22 | 17385618278700 |
| 23 | 86500622296800 |
| 24 | 431718990188850 |
| 25 | 2160826237261692 |