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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 25 |
| 5 | 75 |
| 6 | 227 |
| 7 | 693 |
| 8 | 2139 |
| 9 | 6645 |
| 10 | 20757 |
| 11 | 65139 |
| 12 | 205189 |
| 13 | 648427 |
| 14 | 2054775 |
| 15 | 6526841 |
| 16 | 20775357 |
| 17 | 66251247 |
| 18 | 211617131 |
| 19 | 676930325 |
| 20 | 2168252571 |
| 21 | 6953348149 |
| 22 | 22322825865 |
| 23 | 71735559255 |
| 24 | 230735316795 |
| 25 | 742773456825 |
| 26 | 2392949225565 |
| 27 | 7714727440755 |
| 28 | 24888317247705 |
| 29 | 80341227688095 |