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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 25 |
| 5 | 125 |
| 6 | 633 |
| 7 | 2532 |
| 8 | 10288 |
| 9 | 48776 |
| 10 | 233776 |
| 11 | 1080228 |
| 12 | 4996113 |
| 13 | 23080949 |
| 14 | 107157345 |
| 15 | 501507348 |
| 16 | 2345998289 |
| 17 | 10947914825 |
| 18 | 51111745065 |
| 19 | 238823109920 |
| 20 | 1116507049088 |
| 21 | 5221116919456 |
| 22 | 24414616690816 |
| 23 | 114158428564416 |