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 | 4 |
| 2 | 22 |
| 3 | 134 |
| 4 | 866 |
| 5 | 5812 |
| 6 | 40048 |
| 7 | 281374 |
| 8 | 2006698 |
| 9 | 14482064 |
| 10 | 105527060 |
| 11 | 775113440 |
| 12 | 5731756720 |
| 13 | 42628923040 |
| 14 | 318621793472 |
| 15 | 2391808860446 |
| 16 | 18023208400634 |
| 17 | 136271601087352 |
| 18 | 1033449449559724 |
| 19 | 7858699302115444 |
| 20 | 59906766929537116 |
| 21 | 457685157123172664 |