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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 6 |
| 7 | 134 |
| 8 | 960 |
| 9 | 16615 |
| 10 | 138022 |
| 11 | 2425600 |
| 12 | 23279224 |
| 13 | 444500577 |
| 14 | 4880181294 |
| 15 | 102914967458 |
| 16 | 1277238809792 |
| 17 | 29767443364523 |
| 18 | 412889949481670 |
| 19 | 10588965173821348 |
| 20 | 162515224089696984 |
| 21 | 4560137456338593333 |
| 22 | 76773519570724122126 |
| 23 | 2343258977445039475014 |