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 | 4 |
| 2 | 16 |
| 3 | 60 |
| 4 | 222 |
| 5 | 804 |
| 6 | 2878 |
| 7 | 10192 |
| 8 | 35812 |
| 9 | 125012 |
| 10 | 434110 |
| 11 | 1500912 |
| 12 | 5170626 |
| 13 | 17758812 |
| 14 | 60837880 |
| 15 | 207965356 |
| 16 | 709583398 |
| 17 | 2417278172 |
| 18 | 8223508510 |
| 19 | 27943213944 |
| 20 | 94853465148 |
| 21 | 321696510276 |
| 22 | 1090199408374 |
| 23 | 3692112980824 |
| 24 | 12496559933794 |