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 | 80 |
| 5 | 237 |
| 6 | 701 |
| 7 | 2073 |
| 8 | 6129 |
| 9 | 18120 |
| 10 | 53569 |
| 11 | 158367 |
| 12 | 468181 |
| 13 | 1384083 |
| 14 | 4091760 |
| 15 | 12096453 |
| 16 | 35760689 |
| 17 | 105719157 |
| 18 | 312537041 |
| 19 | 923951760 |
| 20 | 2731474161 |
| 21 | 8075043963 |
| 22 | 23872213729 |
| 23 | 70573310907 |
| 24 | 208635540400 |
| 25 | 616788246957 |
| 26 | 1823408134821 |
| 27 | 5390532719313 |