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 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 60 |
| 5 | 182 |
| 6 | 546 |
| 7 | 1640 |
| 8 | 4920 |
| 9 | 14762 |
| 10 | 44286 |
| 11 | 132860 |
| 12 | 398580 |
| 13 | 1195742 |
| 14 | 3587226 |
| 15 | 10761680 |
| 16 | 32285040 |
| 17 | 96855122 |
| 18 | 290565366 |
| 19 | 871696100 |
| 20 | 2615088300 |
| 21 | 7845264902 |
| 22 | 23535794706 |
| 23 | 70607384120 |
| 24 | 211822152360 |
| 25 | 635466457082 |
| 26 | 1906399371246 |