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 | 1 |
| 2 | 9 |
| 3 | 61 |
| 4 | 481 |
| 5 | 4881 |
| 6 | 55321 |
| 7 | 682669 |
| 8 | 9343041 |
| 9 | 139078081 |
| 10 | 2216425321 |
| 11 | 37736834301 |
| 12 | 683184324769 |
| 13 | 13064452686481 |
| 14 | 262867726142841 |
| 15 | 5549111222344621 |
| 16 | 122499654278797441 |
| 17 | 2819926900630750209 |
| 18 | 67539541277010100681 |
| 19 | 1679557316488693881661 |