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) |
|---|---|
| 4 | 1 |
| 5 | 20 |
| 6 | 130 |
| 7 | 576 |
| 8 | 2218 |
| 9 | 8170 |
| 10 | 29830 |
| 11 | 109192 |
| 12 | 402258 |
| 13 | 1492746 |
| 14 | 5578742 |
| 15 | 20986424 |
| 16 | 79420122 |
| 17 | 302175648 |
| 18 | 1155298598 |
| 19 | 4436375790 |
| 20 | 17103294308 |
| 21 | 66174208076 |
| 22 | 256870951048 |
| 23 | 1000080994758 |
| 24 | 3904276709604 |
| 25 | 15280413966512 |