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 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 15 |
| 6 | 46 |
| 7 | 132 |
| 8 | 432 |
| 9 | 1384 |
| 10 | 4735 |
| 11 | 16158 |
| 12 | 56766 |
| 13 | 200473 |
| 14 | 718012 |
| 15 | 2587000 |
| 16 | 9398080 |
| 17 | 34324173 |
| 18 | 126067124 |
| 19 | 465093570 |
| 20 | 1723171550 |
| 21 | 6407924165 |
| 22 | 23910560070 |
| 23 | 89494164972 |
| 24 | 335913861648 |
| 25 | 1264107416450 |
| 26 | 4768452532025 |