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 | 31 |
| 4 | 217 |
| 5 | 1781 |
| 6 | 16501 |
| 7 | 172915 |
| 8 | 1998641 |
| 9 | 25468777 |
| 10 | 352751941 |
| 11 | 5292123431 |
| 12 | 85297925065 |
| 13 | 1472161501981 |
| 14 | 27039872306357 |
| 15 | 527253067633531 |
| 16 | 10865963240550241 |
| 17 | 236088078855319505 |
| 18 | 5390956470528548101 |
| 19 | 129102989125943058607 |
| 20 | 3234053809095307670201 |
| 21 | 84596120521251178630981 |
| 22 | 2305894874979300173268085 |