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 | 3 |
| 6 | 6 |
| 7 | 26 |
| 8 | 72 |
| 9 | 241 |
| 10 | 623 |
| 11 | 2028 |
| 12 | 5374 |
| 13 | 16781 |
| 14 | 45094 |
| 15 | 138971 |
| 16 | 378196 |
| 17 | 1156028 |
| 18 | 3183390 |
| 19 | 9679303 |
| 20 | 26929415 |
| 21 | 81575661 |
| 22 | 228958790 |