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 | 52 |
| 5 | 425 |
| 6 | 4266 |
| 7 | 52507 |
| 8 | 754944 |
| 9 | 12499209 |
| 10 | 233296030 |
| 11 | 4852006181 |
| 12 | 111149993736 |
| 13 | 2781312439633 |
| 14 | 75460291482772 |
| 15 | 2206445155886805 |
| 16 | 69163853027437216 |
| 17 | 2313709581153992033 |
| 18 | 82271226298253976054 |