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 | 1 |
| 3 | 9 |
| 4 | 81 |
| 5 | 705 |
| 6 | 7665 |
| 7 | 100905 |
| 8 | 1524705 |
| 9 | 26022465 |
| 10 | 496042785 |
| 11 | 10445342985 |
| 12 | 240779831985 |
| 13 | 6030718158465 |
| 14 | 163087008669585 |
| 15 | 4735950860666025 |
| 16 | 146987669673669825 |
| 17 | 4855606200012593025 |
| 18 | 170101350767940617025 |
| 19 | 6298861062893921346825 |
| 20 | 245834199405298416337425 |