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 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 53 |
| 6 | 161 |
| 7 | 485 |
| 8 | 1457 |
| 9 | 4373 |
| 10 | 13121 |
| 11 | 39365 |
| 12 | 118097 |
| 13 | 354293 |
| 14 | 1062881 |
| 15 | 3188645 |
| 16 | 9565937 |
| 17 | 28697813 |
| 18 | 86093441 |
| 19 | 258280325 |
| 20 | 774840977 |
| 21 | 2324522933 |
| 22 | 6973568801 |
| 23 | 20920706405 |
| 24 | 62762119217 |
| 25 | 188286357653 |
| 26 | 564859072961 |