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 | 2 |
| 4 | 2 |
| 5 | 8 |
| 6 | 16 |
| 7 | 52 |
| 8 | 134 |
| 9 | 432 |
| 10 | 1248 |
| 11 | 4104 |
| 12 | 12648 |
| 13 | 42464 |
| 14 | 136512 |
| 15 | 466568 |
| 16 | 1545566 |
| 17 | 5361632 |
| 18 | 18165184 |
| 19 | 63804952 |
| 20 | 219997832 |
| 21 | 780895392 |
| 22 | 2730730176 |
| 23 | 9780049008 |
| 24 | 34598622616 |
| 25 | 124873507904 |
| 26 | 446068180608 |
| 27 | 1620786592416 |
| 28 | 5837657948832 |
| 29 | 21336295622016 |
| 30 | 77395590570240 |