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 | 2 |
| 3 | 8 |
| 4 | 56 |
| 5 | 608 |
| 6 | 9440 |
| 7 | 198272 |
| 8 | 5410688 |
| 9 | 186043904 |
| 10 | 7867739648 |
| 11 | 401293838336 |
| 12 | 24290513745920 |
| 13 | 1721379917619200 |
| 14 | 141174819474169856 |
| 15 | 13266093250285568000 |
| 16 | 1415974941618255921152 |
| 17 | 170361620874699124637696 |
| 18 | 22948071824232932086513664 |
| 19 | 3439933090471867097102680064 |