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 | 1 |
| 3 | 5 |
| 4 | 26 |
| 5 | 245 |
| 6 | 2737 |
| 7 | 35291 |
| 8 | 483819 |
| 9 | 6937913 |
| 10 | 102666626 |
| 11 | 1558022255 |
| 12 | 24133790815 |
| 13 | 380320794122 |
| 14 | 6081804068869 |
| 15 | 98490990290897 |
| 16 | 1612634990857755 |
| 17 | 26660840123167203 |
| 18 | 444560998431678554 |
| 19 | 7469779489114328514 |
| 20 | 126375763235359105446 |
| 21 | 2151342943131421629636 |