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 | 4 |
| 4 | 10 |
| 5 | 26 |
| 6 | 72 |
| 7 | 206 |
| 8 | 606 |
| 9 | 1820 |
| 10 | 5558 |
| 11 | 17206 |
| 12 | 53872 |
| 13 | 170298 |
| 14 | 542778 |
| 15 | 1742308 |
| 16 | 5627698 |
| 17 | 18277698 |
| 18 | 59652952 |
| 19 | 195541494 |
| 20 | 643506310 |
| 21 | 2125255036 |
| 22 | 7041631854 |
| 23 | 23400092142 |
| 24 | 77971706848 |
| 25 | 260458050034 |
| 26 | 872040564850 |
| 27 | 2925902656644 |
| 28 | 9836517749658 |
| 29 | 33130048199466 |