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 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 7 |
| 6 | 19 |
| 7 | 64 |
| 8 | 236 |
| 9 | 893 |
| 10 | 3489 |
| 11 | 14347 |
| 12 | 62429 |
| 13 | 285580 |
| 14 | 1362372 |
| 15 | 6749337 |
| 16 | 34683211 |
| 17 | 184774851 |
| 18 | 1019351071 |
| 19 | 5813020060 |
| 20 | 34206071992 |
| 21 | 207391313189 |
| 22 | 1294092695729 |
| 23 | 8302365433863 |
| 24 | 54713262186745 |
| 25 | 370027343460584 |
| 26 | 2565874205681368 |