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 | 9 |
| 2 | 54 |
| 3 | 264 |
| 4 | 1134 |
| 5 | 4446 |
| 6 | 16272 |
| 7 | 56412 |
| 8 | 187137 |
| 9 | 598417 |
| 10 | 1854882 |
| 11 | 5597172 |
| 12 | 16498632 |
| 13 | 47638512 |
| 14 | 135048672 |
| 15 | 376592064 |
| 16 | 1034663040 |
| 17 | 2804590080 |
| 18 | 7509232640 |
| 19 | 19880294400 |
| 20 | 52088352768 |
| 21 | 135173578752 |
| 22 | 347680161792 |
| 23 | 886900948992 |
| 24 | 2245014454272 |
| 25 | 5641949085696 |