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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 1 |
| 7 | 5 |
| 8 | 19 |
| 9 | 68 |
| 10 | 240 |
| 11 | 839 |
| 12 | 2911 |
| 13 | 10054 |
| 14 | 34641 |
| 15 | 119203 |
| 16 | 409893 |
| 17 | 1408873 |
| 18 | 4841373 |
| 19 | 16634350 |
| 20 | 57149111 |
| 21 | 196333312 |
| 22 | 674477710 |
| 23 | 2317047808 |
| 24 | 7959739375 |
| 25 | 27343914410 |
| 26 | 93933688630 |
| 27 | 322686958885 |
| 28 | 1108513737048 |
| 29 | 3808031504891 |