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 | 6 |
| 2 | 30 |
| 3 | 150 |
| 4 | 750 |
| 5 | 3750 |
| 6 | 18630 |
| 7 | 92406 |
| 8 | 458262 |
| 9 | 2270478 |
| 10 | 11245590 |
| 11 | 55697766 |
| 12 | 275769654 |
| 13 | 1365260862 |
| 14 | 6758345838 |
| 15 | 33450929886 |
| 16 | 165549052326 |
| 17 | 819248589606 |
| 18 | 4054005363918 |