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) |
|---|---|
| 3 | 3 |
| 4 | 19 |
| 5 | 80 |
| 6 | 286 |
| 7 | 945 |
| 8 | 2997 |
| 9 | 9294 |
| 10 | 28456 |
| 11 | 86471 |
| 12 | 261559 |
| 13 | 788892 |
| 14 | 2375010 |
| 15 | 7141581 |
| 16 | 21457705 |
| 17 | 64438874 |
| 18 | 193447948 |
| 19 | 580606275 |
| 20 | 1742343435 |
| 21 | 5228079240 |
| 22 | 15686335270 |
| 23 | 47063200553 |
| 24 | 141197990749 |
| 25 | 423610749990 |
| 26 | 1270865804976 |
| 27 | 3812664524415 |
| 28 | 11438127791647 |