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 | 5 |
| 6 | 20 |
| 7 | 73 |
| 8 | 271 |
| 9 | 974 |
| 10 | 3507 |
| 11 | 12487 |
| 12 | 44475 |
| 13 | 157814 |
| 14 | 559952 |
| 15 | 1985053 |
| 16 | 7040855 |
| 17 | 24986930 |
| 18 | 88782435 |
| 19 | 315911844 |
| 20 | 1126178655 |
| 21 | 4023135764 |
| 22 | 14406870196 |
| 23 | 51728509807 |
| 24 | 186275015554 |
| 25 | 672886200335 |