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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 15 |
| 5 | 87 |
| 6 | 567 |
| 7 | 4167 |
| 8 | 34407 |
| 9 | 316647 |
| 10 | 3219687 |
| 11 | 35878887 |
| 12 | 435046887 |
| 13 | 5704064487 |
| 14 | 80428314087 |
| 15 | 1213746099687 |
| 16 | 19521187251687 |
| 17 | 333363035571687 |
| 18 | 6024361885107687 |
| 19 | 114864714882483687 |
| 20 | 2304476522241459687 |
| 21 | 48529614677597619687 |
| 22 | 1070348458111786419687 |