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 | 3 |
| 2 | 9 |
| 3 | 20 |
| 4 | 53 |
| 5 | 117 |
| 6 | 308 |
| 7 | 684 |
| 8 | 1806 |
| 9 | 4028 |
| 10 | 10664 |
| 11 | 23844 |
| 12 | 63239 |
| 13 | 141612 |
| 14 | 376026 |
| 15 | 842866 |
| 16 | 2239900 |
| 17 | 5024166 |
| 18 | 13359408 |
| 19 | 29980384 |
| 20 | 79753402 |
| 21 | 179044760 |
| 22 | 476451644 |
| 23 | 1069936084 |
| 24 | 2847931619 |
| 25 | 6396900694 |
| 26 | 17030741437 |
| 27 | 38260956765 |