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 | 3 |
| 2 | 15 |
| 3 | 105 |
| 4 | 933 |
| 5 | 9951 |
| 6 | 123123 |
| 7 | 1727685 |
| 8 | 27050985 |
| 9 | 466795323 |
| 10 | 8791179831 |
| 11 | 179262508833 |
| 12 | 3931730998605 |
| 13 | 92237649141015 |
| 14 | 2303515063987803 |
| 15 | 60987344488950141 |
| 16 | 1705641174191204433 |
| 17 | 50228924171214633075 |
| 18 | 1553143164997199612895 |