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 | 3 |
| 3 | 9 |
| 4 | 37 |
| 5 | 225 |
| 6 | 1881 |
| 7 | 19873 |
| 8 | 251889 |
| 9 | 3712257 |
| 10 | 62286625 |
| 11 | 1171487361 |
| 12 | 24402416193 |
| 13 | 557542291969 |
| 14 | 13861636770177 |
| 15 | 372514645389825 |
| 16 | 10759590258589441 |
| 17 | 332386419622387713 |
| 18 | 10935312198369141249 |
| 19 | 381705328034883127297 |
| 20 | 14089260601787531469825 |
| 21 | 548302210950105933701121 |