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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 10 |
| 6 | 28 |
| 7 | 106 |
| 8 | 344 |
| 9 | 1272 |
| 10 | 4592 |
| 11 | 17692 |
| 12 | 69384 |
| 13 | 283560 |
| 14 | 1191984 |
| 15 | 5171512 |
| 16 | 23087168 |
| 17 | 105883456 |
| 18 | 498572416 |
| 19 | 2404766224 |
| 20 | 11878871456 |
| 21 | 59975885856 |
| 22 | 309439708352 |
| 23 | 1628919330208 |
| 24 | 8746079933568 |
| 25 | 47840206525056 |