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 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 88 |
| 6 | 368 |
| 7 | 1584 |
| 8 | 6968 |
| 9 | 31192 |
| 10 | 141656 |
| 11 | 651136 |
| 12 | 3023840 |
| 13 | 14166496 |
| 14 | 66876096 |
| 15 | 317809216 |
| 16 | 1519163456 |
| 17 | 7299577216 |
| 18 | 35237444736 |
| 19 | 170812433536 |
| 20 | 831127053696 |
| 21 | 4057858988416 |
| 22 | 19873611712896 |
| 23 | 97609555091456 |