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 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 38 |
| 5 | 210 |
| 6 | 1339 |
| 7 | 9870 |
| 8 | 82368 |
| 9 | 768432 |
| 10 | 7926903 |
| 11 | 89610070 |
| 12 | 1101767732 |
| 13 | 14639237184 |
| 14 | 209048293375 |
| 15 | 3192959638778 |
| 16 | 51943905125760 |
| 17 | 896723236236864 |
| 18 | 16373101528868943 |
| 19 | 315259605244694574 |
| 20 | 6384318171252621716 |
| 21 | 135651088007338895680 |
| 22 | 3017472066675257000775 |