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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 25 |
| 6 | 110 |
| 7 | 721 |
| 8 | 6286 |
| 9 | 57625 |
| 10 | 541470 |
| 11 | 5558641 |
| 12 | 64351166 |
| 13 | 819480025 |
| 14 | 11140978030 |
| 15 | 160711583761 |
| 16 | 2472834185646 |
| 17 | 40597082635225 |
| 18 | 706816137889790 |
| 19 | 12974021811748081 |
| 20 | 250395124862965726 |
| 21 | 5074637684604691225 |
| 22 | 107798916619788396750 |