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 | 9 |
| 2 | 81 |
| 3 | 221 |
| 4 | 663 |
| 5 | 2245 |
| 6 | 6459 |
| 7 | 17563 |
| 8 | 48649 |
| 9 | 131269 |
| 10 | 344873 |
| 11 | 902075 |
| 12 | 2342619 |
| 13 | 6021103 |
| 14 | 15395621 |
| 15 | 39219821 |
| 16 | 99470227 |
| 17 | 251449497 |
| 18 | 634148313 |
| 19 | 1595707571 |
| 20 | 4007571389 |
| 21 | 10049914241 |
| 22 | 25169768531 |
| 23 | 62965428327 |
| 24 | 157368593823 |
| 25 | 392995561393 |