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 | 5 |
| 3 | 18 |
| 4 | 72 |
| 5 | 2054 |
| 6 | 53608 |
| 7 | 1744887 |
| 8 | 216103851 |
| 9 | 39184763856 |
| 10 | 11314547102638 |
| 11 | 7873316318240100 |
| 12 | 9711485486581483616 |
| 13 | 21262647899259681841579 |