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) |
|---|---|
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 20 |
| 6 | 60 |
| 7 | 176 |
| 8 | 517 |
| 9 | 1512 |
| 10 | 4415 |
| 11 | 12870 |
| 12 | 37477 |
| 13 | 109044 |
| 14 | 317109 |
| 15 | 921870 |
| 16 | 2679510 |
| 17 | 7787904 |
| 18 | 22636503 |
| 19 | 65804638 |
| 20 | 191332945 |
| 21 | 556456060 |
| 22 | 1618813834 |
| 23 | 4710869108 |
| 24 | 13713658368 |
| 25 | 39935698400 |
| 26 | 116340344575 |
| 27 | 339050396646 |
| 28 | 988474306017 |