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) |
|---|---|
| 1 | 6 |
| 2 | 36 |
| 3 | 102 |
| 4 | 270 |
| 5 | 798 |
| 6 | 2354 |
| 7 | 7210 |
| 8 | 22232 |
| 9 | 69570 |
| 10 | 218950 |
| 11 | 693810 |
| 12 | 2207142 |
| 13 | 7047274 |
| 14 | 22559004 |
| 15 | 72371822 |
| 16 | 232562110 |
| 17 | 748347990 |
| 18 | 2410664906 |
| 19 | 7772348106 |
| 20 | 25076879856 |
| 21 | 80954866538 |
| 22 | 261464311606 |
| 23 | 844780530762 |
| 24 | 2730274274910 |
| 25 | 8826217794378 |