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 | 4 |
| 3 | 28 |
| 4 | 352 |
| 5 | 7696 |
| 6 | 296704 |
| 7 | 19845568 |
| 8 | 2325071872 |
| 9 | 472050401536 |
| 10 | 167325747134464 |
| 11 | 102717666720160768 |
| 12 | 109887628080679616512 |
| 13 | 203517277347030338768896 |
| 14 | 656102983404750860283019264 |
| 15 | 3660938644168893995628877692928 |