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 | 3 |
| 4 | 7 |
| 5 | 55 |
| 6 | 307 |
| 7 | 6153 |
| 8 | 82977 |
| 9 | 4196961 |
| 10 | 137460201 |
| 11 | 17446527483 |
| 12 | 1392263902567 |
| 13 | 441865841817751 |
| 14 | 86102618147479627 |
| 15 | 68171466271082093265 |
| 16 | 32487634563234662295169 |
| 17 | 64060941478203660710291329 |
| 18 | 74749048993664905589266454929 |
| 19 | 366627599282115135074804792982963 |