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 | 0 |
| 1 | 4 |
| 2 | 16 |
| 3 | 66 |
| 4 | 244 |
| 5 | 968 |
| 6 | 3726 |
| 7 | 14520 |
| 8 | 56352 |
| 9 | 218978 |
| 10 | 850620 |
| 11 | 3304624 |
| 12 | 12837742 |
| 13 | 49872976 |
| 14 | 193747784 |
| 15 | 752680930 |
| 16 | 2924043092 |
| 17 | 11359448344 |
| 18 | 44129645550 |
| 19 | 171436683864 |
| 20 | 666004286592 |
| 21 | 2587320999714 |
| 22 | 10051331417116 |
| 23 | 39047827550656 |