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) |
|---|---|
| 3 | 1 |
| 4 | 9 |
| 5 | 51 |
| 6 | 279 |
| 7 | 1277 |
| 8 | 6235 |
| 9 | 26789 |
| 10 | 125370 |
| 11 | 525082 |
| 12 | 2409886 |
| 13 | 9969722 |
| 14 | 45289767 |
| 15 | 186105280 |
| 16 | 840402559 |
| 17 | 3439358196 |
| 18 | 15472942142 |
| 19 | 63155131233 |
| 20 | 283400162019 |