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 | 5 |
| 3 | 24 |
| 4 | 104 |
| 5 | 432 |
| 6 | 1736 |
| 7 | 6820 |
| 8 | 26332 |
| 9 | 100308 |
| 10 | 377996 |
| 11 | 1411844 |
| 12 | 5234428 |
| 13 | 19285252 |
| 14 | 70670972 |
| 15 | 257766212 |
| 16 | 936336572 |
| 17 | 3388962884 |
| 18 | 12226547132 |
| 19 | 43983439684 |
| 20 | 157814634684 |
| 21 | 564917186372 |
| 22 | 2017873643708 |
| 23 | 7193745818436 |