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 | 27 |
| 4 | 79 |
| 5 | 225 |
| 6 | 627 |
| 7 | 1717 |
| 8 | 4633 |
| 9 | 12341 |
| 10 | 32501 |
| 11 | 84737 |
| 12 | 218959 |
| 13 | 561263 |
| 14 | 1428287 |
| 15 | 3610671 |
| 16 | 9072367 |
| 17 | 22668285 |
| 18 | 56345835 |
| 19 | 139382713 |
| 20 | 343242533 |
| 21 | 841713531 |
| 22 | 2055944117 |
| 23 | 5003148987 |
| 24 | 12132552115 |
| 25 | 29323810757 |
| 26 | 70651867863 |
| 27 | 169719163521 |
| 28 | 406541986857 |
| 29 | 971192810019 |