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 | 2 |
| 2 | 9 |
| 3 | 36 |
| 4 | 156 |
| 5 | 698 |
| 6 | 3210 |
| 7 | 15080 |
| 8 | 72060 |
| 9 | 349184 |
| 10 | 1711869 |
| 11 | 8475494 |
| 12 | 42318018 |
| 13 | 212843826 |
| 14 | 1077391794 |
| 15 | 5484472880 |
| 16 | 28058940086 |
| 17 | 144195777552 |
| 18 | 744017466318 |
| 19 | 3852968380624 |
| 20 | 20019113126120 |
| 21 | 104329129258596 |
| 22 | 545214946753377 |