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 | 6 |
| 4 | 24 |
| 5 | 6 |
| 6 | 30 |
| 7 | 66 |
| 8 | 228 |
| 9 | 978 |
| 10 | 456 |
| 11 | 2412 |
| 12 | 5736 |
| 13 | 22032 |
| 14 | 99600 |
| 15 | 66096 |
| 16 | 364896 |
| 17 | 928080 |
| 18 | 3878928 |
| 19 | 18299952 |
| 20 | 15515712 |
| 21 | 88715520 |
| 22 | 239493888 |
| 23 | 1073343744 |
| 24 | 5251350528 |
| 25 | 239493888 |
| 26 | 1312837632 |
| 27 | 7877025792 |
| 28 | 23870571264 |
| 29 | 96795122688 |