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 | 4 |
| 2 | 27 |
| 3 | 187 |
| 4 | 1302 |
| 5 | 9075 |
| 6 | 63267 |
| 7 | 441090 |
| 8 | 3075255 |
| 9 | 21440547 |
| 10 | 149482638 |
| 11 | 1042187067 |
| 12 | 7266087315 |
| 13 | 50658875658 |
| 14 | 353191693599 |
| 15 | 2462438631411 |
| 16 | 17168025532662 |
| 17 | 119694800484387 |
| 18 | 834507453158019 |
| 19 | 5818153224352338 |
| 20 | 40563936024707079 |
| 21 | 282810170576026755 |