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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 16 |
| 6 | 136 |
| 7 | 736 |
| 8 | 4096 |
| 9 | 20224 |
| 10 | 99856 |
| 11 | 475696 |
| 12 | 3889216 |
| 13 | 31778176 |
| 14 | 313696384 |
| 15 | 2709911296 |
| 16 | 23006784256 |
| 17 | 179965340416 |
| 18 | 1532217039616 |
| 19 | 13081112406784 |
| 20 | 147235213351936 |
| 21 | 1657791879049216 |
| 22 | 20132199908571136 |
| 23 | 226466449808367616 |
| 24 | 2542933338768769024 |