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 | 12 |
| 4 | 36 |
| 5 | 135 |
| 6 | 432 |
| 7 | 1539 |
| 8 | 4860 |
| 9 | 17496 |
| 10 | 55404 |
| 11 | 192456 |
| 12 | 623295 |
| 13 | 2125764 |
| 14 | 6849684 |
| 15 | 23442453 |
| 16 | 75110328 |
| 17 | 252965916 |
| 18 | 822670668 |
| 19 | 2735858268 |
| 20 | 8838926712 |
| 21 | 29501352792 |
| 22 | 95090206689 |
| 23 | 314068876416 |
| 24 | 1018141045092 |
| 25 | 3342663979092 |
| 26 | 10798571289897 |
| 27 | 35481518064576 |