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 | 2 |
| 2 | 9 |
| 3 | 57 |
| 4 | 441 |
| 5 | 3933 |
| 6 | 39249 |
| 7 | 430677 |
| 8 | 5137641 |
| 9 | 66103533 |
| 10 | 911973249 |
| 11 | 13428837477 |
| 12 | 210259505241 |
| 13 | 3489291147933 |
| 14 | 61200522593649 |
| 15 | 1131630622515477 |
| 16 | 22007781151434441 |
| 17 | 449197758198576333 |
| 18 | 9603342828706622049 |