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) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 30 |
| 3 | 114 |
| 4 | 438 |
| 5 | 1542 |
| 6 | 5754 |
| 7 | 19574 |
| 8 | 71958 |
| 9 | 233574 |
| 10 | 870666 |
| 11 | 2696274 |
| 12 | 10375770 |
| 13 | 30198116 |
| 14 | 122634404 |
| 15 | 327024444 |
| 16 | 1460721616 |
| 17 | 3347244554 |
| 18 | 17795165832 |