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) |
|---|---|
| 2 | 1 |
| 3 | 7 |
| 4 | 28 |
| 5 | 123 |
| 6 | 515 |
| 7 | 2192 |
| 8 | 9269 |
| 9 | 39291 |
| 10 | 166396 |
| 11 | 704935 |
| 12 | 2986039 |
| 13 | 12649248 |
| 14 | 53582777 |
| 15 | 226980767 |
| 16 | 961505180 |
| 17 | 4073002563 |
| 18 | 17253513691 |
| 19 | 73087060144 |
| 20 | 309601749709 |
| 21 | 1311494066355 |
| 22 | 5555578003196 |
| 23 | 23533806098447 |
| 24 | 99690802365743 |
| 25 | 422297015611968 |
| 26 | 1788878864731825 |