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 | 4 |
| 2 | 42 |
| 3 | 660 |
| 4 | 12810 |
| 5 | 281736 |
| 6 | 6727644 |
| 7 | 170316432 |
| 8 | 4504487130 |
| 9 | 123255492360 |
| 10 | 3465702008340 |
| 11 | 99645553785960 |
| 12 | 2918768920720380 |
| 13 | 86852063374902000 |
| 14 | 2619552500788984200 |
| 15 | 79939673971478231760 |