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) |
|---|---|
| 3 | 1 |
| 4 | 2 |
| 5 | 7 |
| 6 | 24 |
| 7 | 81 |
| 8 | 270 |
| 9 | 886 |
| 10 | 2861 |
| 11 | 9109 |
| 12 | 28652 |
| 13 | 89211 |
| 14 | 275420 |
| 15 | 844320 |
| 16 | 2573161 |
| 17 | 7803656 |
| 18 | 23569375 |
| 19 | 70941900 |
| 20 | 212911167 |
| 21 | 637427166 |
| 22 | 1904416809 |
| 23 | 5679745126 |
| 24 | 16913962409 |
| 25 | 50304623519 |
| 26 | 149450737592 |
| 27 | 443593524167 |
| 28 | 1315613998440 |