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) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 15 |
| 3 | 87 |
| 4 | 585 |
| 5 | 4383 |
| 6 | 35919 |
| 7 | 318195 |
| 8 | 3015441 |
| 9 | 30354075 |
| 10 | 322626159 |
| 11 | 3603292047 |
| 12 | 42120047385 |
| 13 | 513557128503 |
| 14 | 6512375759535 |
| 15 | 85673471945067 |
| 16 | 1166675225150241 |
| 17 | 16413589529042355 |
| 18 | 238151194659626319 |
| 19 | 3558129109803374535 |