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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 40 |
| 5 | 514 |
| 6 | 4909 |
| 7 | 43851 |
| 8 | 384738 |
| 9 | 3351032 |
| 10 | 29189691 |
| 11 | 255371697 |
| 12 | 2246576317 |
| 13 | 19878698732 |
| 14 | 176913444597 |
| 15 | 1583135619012 |
| 16 | 14240370591853 |
| 17 | 128711774414592 |
| 18 | 1168583066366245 |