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 | 1 |
| 4 | 3 |
| 5 | 9 |
| 6 | 27 |
| 7 | 75 |
| 8 | 197 |
| 9 | 503 |
| 10 | 1263 |
| 11 | 3132 |
| 12 | 7695 |
| 13 | 18784 |
| 14 | 45649 |
| 15 | 110585 |
| 16 | 267276 |
| 17 | 644907 |
| 18 | 1554208 |
| 19 | 3742321 |
| 20 | 9005265 |
| 21 | 21659603 |
| 22 | 52078400 |
| 23 | 125186565 |
| 24 | 300870586 |
| 25 | 723010749 |
| 26 | 1737273406 |
| 27 | 4174084259 |
| 28 | 10028409724 |
| 29 | 24092769583 |
| 30 | 57880137331 |