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 | 1 |
| 5 | 2 |
| 6 | 5 |
| 7 | 17 |
| 8 | 49 |
| 9 | 138 |
| 10 | 374 |
| 11 | 1062 |
| 12 | 2851 |
| 13 | 8010 |
| 14 | 21432 |
| 15 | 60142 |
| 16 | 161386 |
| 17 | 453253 |
| 18 | 1222110 |
| 19 | 3436564 |
| 20 | 9316409 |
| 21 | 26231463 |
| 22 | 71496106 |