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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 9 |
| 5 | 51 |
| 6 | 233 |
| 7 | 939 |
| 8 | 3489 |
| 9 | 12259 |
| 10 | 41385 |
| 11 | 135675 |
| 12 | 435185 |
| 13 | 1373139 |
| 14 | 4279161 |
| 15 | 13210219 |
| 16 | 40490817 |
| 17 | 123438531 |
| 18 | 374772041 |
| 19 | 1134343131 |
| 20 | 3425442705 |
| 21 | 10326135475 |
| 22 | 31088506905 |
| 23 | 93507741771 |
| 24 | 281053804769 |
| 25 | 844319042211 |
| 26 | 2535473709033 |
| 27 | 7611873722299 |
| 28 | 22847398772529 |
| 29 | 68567563468179 |