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 | 126 |
| 3 | 2109 |
| 4 | 38916 |
| 5 | 763686 |
| 6 | 15636192 |
| 7 | 330237765 |
| 8 | 7141879503 |
| 9 | 157366449604 |
| 10 | 3520256293710 |
| 11 | 79735912636302 |
| 12 | 1825080422272800 |
| 13 | 42148579533938784 |
| 14 | 980892581545169496 |
| 15 | 22980848343194476245 |
| 16 | 541581608172776494554 |
| 17 | 12829884648994115426295 |
| 18 | 305349921559399354716430 |