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 | 2 |
| 1 | 5 |
| 2 | 16 |
| 3 | 55 |
| 4 | 196 |
| 5 | 714 |
| 6 | 2640 |
| 7 | 9867 |
| 8 | 37180 |
| 9 | 140998 |
| 10 | 537472 |
| 11 | 2057510 |
| 12 | 7904456 |
| 13 | 30458900 |
| 14 | 117675360 |
| 15 | 455657715 |
| 16 | 1767883500 |
| 17 | 6871173870 |
| 18 | 26747767200 |
| 19 | 104268528210 |
| 20 | 406975466040 |
| 21 | 1590307356300 |
| 22 | 6220814327520 |
| 23 | 24357232569150 |
| 24 | 95452906901976 |
| 25 | 374369872911804 |