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 | 5 |
| 5 | 21 |
| 6 | 78 |
| 7 | 274 |
| 8 | 927 |
| 9 | 3061 |
| 10 | 9933 |
| 11 | 31824 |
| 12 | 100972 |
| 13 | 317942 |
| 14 | 995088 |
| 15 | 3099105 |
| 16 | 9612735 |
| 17 | 29715525 |
| 18 | 91595391 |
| 19 | 281643480 |
| 20 | 864189486 |
| 21 | 2646805668 |
| 22 | 8093543439 |
| 23 | 24713953515 |
| 24 | 75370741506 |
| 25 | 229604257846 |
| 26 | 698754428388 |
| 27 | 2124616182139 |