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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 15 |
| 5 | 59 |
| 6 | 241 |
| 7 | 1011 |
| 8 | 4326 |
| 9 | 18797 |
| 10 | 82685 |
| 11 | 367410 |
| 12 | 1646494 |
| 13 | 7432270 |
| 14 | 33761322 |
| 15 | 154213566 |
| 16 | 707882503 |
| 17 | 3263713148 |
| 18 | 15107319268 |
| 19 | 70182332975 |
| 20 | 327111450097 |
| 21 | 1529226524057 |
| 22 | 7168880978609 |
| 23 | 33693179852563 |